Benefits of Moderate-Intensity Exercise during a Calorie-Restricted Low-Fat Diet

ERIC Educational Resources Information Center

Apekey, Tanefa A.; Morris, A. E. J.; Fagbemi, S.; Griffiths, G. J.

2012-01-01

Objective: Despite the health benefits, many people do not undertake regular exercise. This study investigated the effects of moderate-intensity exercise on cardiorespiratory fitness (lung age, blood pressure and maximal aerobic power, VO[subscript 2]max), serum lipids concentration and body mass index (BMI) in sedentary overweight/obese adults…

Aerobic Capacity in Children and Adolescents with Cerebral Palsy

ERIC Educational Resources Information Center

Verschuren, Olaf; Takken, Tim

2010-01-01

This study described the aerobic capacity [VO[subscript 2peak] (ml/kg/min)] in contemporary children and adolescents with cerebral palsy (CP) using a maximal exercise test protocol. Twenty-four children and adolescents with CP classified at Gross Motor Functional Classification Scale (GMFCS) level I or level II and 336 typically developing…

A Primer-Test Centered Equating Method for Setting Cut-Off Scores

ERIC Educational Resources Information Center

Zhu, Weimo; Plowman, Sharon Ann; Park, Youngsik

2010-01-01

This study evaluated the use of a new primary field test method based on test equating to address inconsistent classification among field tests. We analyzed students' information on the Progressive Aerobic Cardiovascular Endurance Run (PACER), mile run (MR), and VO[subscript 2]max from three data sets (college: n = 94; middle school: n = 39;…

21 CFR 868.1730 - Oxygen uptake computer.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Oxygen uptake computer. 868.1730 Section 868.1730...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1730 Oxygen uptake computer. (a) Identification. An oxygen uptake computer is a device intended to compute the amount of oxygen consumed by a...

21 CFR 868.1730 - Oxygen uptake computer.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Oxygen uptake computer. 868.1730 Section 868.1730...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1730 Oxygen uptake computer. (a) Identification. An oxygen uptake computer is a device intended to compute the amount of oxygen consumed by a...

21 CFR 868.1730 - Oxygen uptake computer.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Oxygen uptake computer. 868.1730 Section 868.1730...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1730 Oxygen uptake computer. (a) Identification. An oxygen uptake computer is a device intended to compute the amount of oxygen consumed by a...

21 CFR 868.1730 - Oxygen uptake computer.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Oxygen uptake computer. 868.1730 Section 868.1730...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1730 Oxygen uptake computer. (a) Identification. An oxygen uptake computer is a device intended to compute the amount of oxygen consumed by a...

21 CFR 868.1730 - Oxygen uptake computer.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Oxygen uptake computer. 868.1730 Section 868.1730...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1730 Oxygen uptake computer. (a) Identification. An oxygen uptake computer is a device intended to compute the amount of oxygen consumed by a...

Development of 1-Mile Walk Tests to Estimate Aerobic Fitness in Children

ERIC Educational Resources Information Center

Sung, Hoyong; Collier, David N.; DuBose, Katrina D.; Kemble, C. David; Mahar, Matthew T.

2018-01-01

To examine the reliability and validity of 1-mile walk tests for estimation of aerobic fitness (VO[subscript 2max]) in 10- to 13-year-old children and to cross-validate previously published equations. Participants (n = 61) walked 1-mile on two different days. Self-reported physical activity, demographic variables, and aerobic fitness were used in…

The interrelationship between muscle oxygenation, muscle activation, and pulmonary oxygen uptake to incremental ramp exercise: influence of aerobic fitness.

PubMed

Boone, Jan; Barstow, Thomas J; Celie, Bert; Prieur, Fabrice; Bourgois, Jan

2016-01-01

We investigated whether muscle and ventilatory responses to incremental ramp exercise would be influenced by aerobic fitness status by means of a cross-sectional study with a large subject population. Sixty-four male students (age: 21.2 ± 3.2 years) with a heterogeneous peak oxygen uptake (51.9 ± 6.3 mL·min(-1)·kg(-1), range 39.7-66.2 mL·min(-1)·kg(-1)) performed an incremental ramp cycle test (20-35 W·min(-1)) to exhaustion. Breath-by-breath gas exchange was recorded, and muscle activation and oxygenation were measured with surface electromyography and near-infrared spectroscopy, respectively. The integrated electromyography (iEMG), mean power frequency (MPF), deoxygenated [hemoglobin and myoglobin] (deoxy[Hb+Mb]), and total[Hb+Mb] responses were set out as functions of work rate and fitted with a double linear function. The respiratory compensation point (RCP) was compared and correlated with the breakpoints (BPs) (as percentage of peak oxygen uptake) in muscle activation and oxygenation. The BP in total[Hb+Mb] (83.2% ± 3.0% peak oxygen uptake) preceded (P < 0.001) the BP in iEMG (86.7% ± 4.0% peak oxygen uptake) and MPF (86.3% ± 4.1% peak oxygen uptake), which in turn preceded (P < 0.01) the BP in deoxy[Hb+Mb] (88.2% ± 4.5% peak oxygen uptake) and RCP (87.4% ± 4.5% peak oxygen uptake). Furthermore, the peak oxygen uptake was significantly (P < 0.001) positively correlated to the BPs and RCP, indicating that the BPs in total[Hb+Mb] (r = 0.66; P < 0.001), deoxy[Hb+Mb] (r = 0.76; P < 0.001), iEMG (r = 0.61; P < 0.001), MPF (r = 0.63; P < 0.001), and RCP (r = 0.75; P < 0.001) occurred at a higher percentage of peak oxygen uptake in subjects with a higher peak oxygen uptake. In this study a close relationship between muscle oxygenation, activation, and pulmonary oxygen uptake was found, occurring in a cascade of events. In subjects with a higher aerobic fitness level this cascade occurred at a higher relative intensity.

The effects of intensity on V̇O2 kinetics during incremental free swimming.

PubMed

de Jesus, Kelly; Sousa, Ana; de Jesus, Karla; Ribeiro, João; Machado, Leandro; Rodríguez, Ferran; Keskinen, Kari; Vilas-Boas, João Paulo; Fernandes, Ricardo J

2015-09-01

Swimming and training are carried out with wide variability in distances and intensities. However, oxygen uptake kinetics for the intensities seen in swimming has not been reported. The purpose of this study was to assess and compare the oxygen uptake kinetics throughout low-moderate to severe intensities during incremental swimming exercise. We hypothesized that the oxygen uptake kinetic parameters would be affected by swimming intensity. Twenty male trained swimmers completed an incremental protocol of seven 200-m crawl swims to exhaustion (0.05 m·s(-1) increments and 30-s intervals). Oxygen uptake was continuously measured by a portable gas analyzer connected to a respiratory snorkel and valve system. Oxygen uptake kinetics was assessed using a double exponential regression model that yielded both fast and slow components of the response of oxygen uptake to exercise. From low-moderate to severe swimming intensities changes occurred for the first and second oxygen uptake amplitudes (P ≤ 0.04), time constants (P = 0.01), and time delays (P ≤ 0.02). At the heavy and severe intensities, a notable oxygen uptake slow component (>255 mL·min(-1)) occurred in all swimmers. Oxygen uptake kinetics whilst swimming at different intensities offers relevant information regarding cardiorespiratory and metabolic stress that might be useful for appropriate performance diagnosis and training prescription.

Coupling of methylmercury uptake with respiration and water pumping in freshwater tilapia Oreochromis niloticus.

PubMed

Wang, Rui; Wong, Ming-Hung; Wang, Wen-Xiong

2011-09-01

The relationships among the uptake of toxic methylmercury (MeHg) and two important fish physiological processes-respiration and water pumping--in the Nile tilapia (Oreochromis niloticus) were explored in the present study. Coupled radiotracer and respirometric techniques were applied to measure simultaneously the uptake rates of MeHg, water, and oxygen under various environmental conditions (temperature, dissolved oxygen level, and water flow). A higher temperature enhanced MeHg influx and the oxygen consumption rate but had no effect on the water uptake, indicating the influence of metabolism on MeHg uptake. The fish showed a high tolerance to hypoxia, and the oxygen consumption rate was not affected until the dissolved oxygen concentration decreased to extremely low levels (below 1 mg/L). The MeHg and water uptake rates increased simultaneously as the dissolved oxygen level decreased, suggesting the coupling of water flux and MeHg uptake. The influence of fish swimming performance on MeHg uptake was also investigated for the first time. Rapidly swimming fish showed significantly higher uptake rates of MeHg, water, and oxygen, confirming the coupling relationships among respiration, water pumping, and metal uptake. Moreover, these results support that MeHg uptake is a rate-limiting process involving energy. Our study demonstrates the importance of physiological processes in understanding mercury bioaccumulation in fluctuating aquatic environments. Copyright © 2011 SETAC.

OXYGEN UPTAKE BEFORE AND AFTER THE ONSET OF CLAUDICATION DURING A 6-MINUTE WALK TEST

PubMed Central

Gardner, Andrew W.; Ritti-Dias, Raphael M.; Stoner, Julie A.; Montgomery, Polly S.; Khurana, Aman; Blevins, Steve M.

2011-01-01

Purposes To compare oxygen uptake before and after the onset of claudication in subjects with peripheral artery disease (PAD) during a 6-minute walk test, and to identify predictors of the change in oxygen uptake following the onset of claudication pain Methods Fifty subjects with PAD were studied, in which 33 experienced claudication (Pain Group) during a 6-minute walk test, and 17 were pain-free during this test (Pain-Free Group). Oxygen uptake and ambulatory cadence were primary outcomes obtained during the 6-minute walk test. Results The Pain Group experienced onset of claudication pain at 179 ± 45 meters (mean ± standard deviation) and continued to walk to achieve a 6-minute walk distance of 393 ± 74 meters, which was similar (p = 0.74) to the Pain-Free Group (401 ± 76 meters). Oxygen uptake increased (p < 0.0001) after the onset of pain in the Pain Group, and this change was greater (p = 0.025) than the increase in oxygen uptake from the second to fifth minute of walking in the Pain-Free Group. Furthermore, ambulatory cadence decreased after the onset of pain in the Pain Group (p = 0.0003). The change in oxygen uptake was associated with metabolic syndrome (p = 0.0023), 6-minute walk distance (p = 0.0037), age, (p = 0.0041), and the oxygen uptake during the second minute of the test (p = 0.012). Conclusion Claudication increases oxygen uptake of self-paced, over-ground ambulation despite a decrease in cadence. The pain-mediated increase in oxygen uptake was blunted in subjects with metabolic syndrome, suggesting that they have an impaired ability to increase oxygen uptake during ambulation. The clinical significance is that claudication increases metabolic cost of ambulation, thereby increasing the relative intensity of exercise and reducing the tolerance to sustain ambulation. PMID:21890308

Heart Rate and Oxygen Uptake Kinetics in Type 2 Diabetes Patients - A Pilot Study on the Influence of Cardiovascular Medication on Regulatory Processes.

PubMed

Koschate, Jessica; Drescher, Uwe; Baum, Klaus; Brinkmann, Christian; Schiffer, Thorsten; Latsch, Joachim; Brixius, Klara; Hoffmann, Uwe

2017-05-01

The aim of this pilot study was to investigate whether there are differences in heart rate and oxygen uptake kinetics in type 2 diabetes patients, considering their cardiovascular medication. It was hypothesized that cardiovascular medication would affect heart rate and oxygen uptake kinetics and that this could be detected using a standardized exercise test. 18 subjects were tested for maximal oxygen uptake. Kinetics were measured in a single test session with standardized, randomized moderate-intensity work rate changes. Time series analysis was used to estimate kinetics. Greater maxima in cross-correlation functions indicate faster kinetics. 6 patients did not take any cardiovascular medication, 6 subjects took peripherally acting medication and 6 patients were treated with centrally acting medication. Maximum oxygen uptake was not significantly different between groups. Significant main effects were identified regarding differences in muscular oxygen uptake kinetics and heart rate kinetics. Muscular oxygen uptake kinetics were significantly faster than heart rate kinetics in the group with no cardiovascular medication (maximum in cross-correlation function of muscular oxygen uptake vs. heart rate; 0.32±0.08 vs. 0.25±0.06; p=0.001) and in the group taking peripherally acting medication (0.34±0.05 vs. 0.28±0.05; p=0.009) but not in the patients taking centrally acting medication (0.28±0.05 vs. 0.30±0.07; n.s.). It can be concluded that regulatory processes for the achievement of a similar maximal oxygen uptake are different between the groups. The used standardized test provided plausible results for heart rate and oxygen uptake kinetics in a single measurement session in this patient group. © Georg Thieme Verlag KG Stuttgart · New York.

Submaximal oxygen uptake kinetics, functional mobility, and physical activity in older adults with heart failure and reduced ejection fraction

PubMed Central

Hummel, Scott L; Herald, John; Alpert, Craig; Gretebeck, Kimberlee A; Champoux, Wendy S; Dengel, Donald R; Vaitkevicius, Peter V; Alexander, Neil B

2016-01-01

Background Submaximal oxygen uptake measures are more feasible and may better predict clinical cardiac outcomes than maximal tests in older adults with heart failure (HF). We examined relationships between maximal oxygen uptake, submaximal oxygen kinetics, functional mobility, and physical activity in older adults with HF and reduced ejection fraction. Methods Older adults with HF and reduced ejection fraction (n = 25, age 75 ± 7 years) were compared to 25 healthy age- and gender-matched controls. Assessments included a maximal treadmill test for peak oxygen uptake (VO2peak), oxygen uptake kinetics at onset of and on recovery from a submaximal treadmill test, functional mobility testing [Get Up and Go (GUG), Comfortable Gait Speed (CGS), Unipedal Stance (US)], and self-reported physical activity (PA). Results Compared to controls, HF had worse performance on GUG, CGS, and US, greater delays in submaximal oxygen uptake kinetics, and lower PA. In controls, VO2peak was more strongly associated with functional mobility and PA than submaximal oxygen uptake kinetics. In HF patients, submaximal oxygen uptake kinetics were similarly associated with GUG and CGS as VO2peak, but weakly associated with PA. Conclusions Based on their mobility performance, older HF patients with reduced ejection fraction are at risk for adverse functional outcomes. In this population, submaximal oxygen uptake measures may be equivalent to VO2 peak in predicting functional mobility, and in addition to being more feasible, may provide better insight into how aerobic function relates to mobility in older adults with HF. PMID:27594875

Submaximal oxygen uptake kinetics, functional mobility, and physical activity in older adults with heart failure and reduced ejection fraction.

PubMed

Hummel, Scott L; Herald, John; Alpert, Craig; Gretebeck, Kimberlee A; Champoux, Wendy S; Dengel, Donald R; Vaitkevicius, Peter V; Alexander, Neil B

2016-07-01

Submaximal oxygen uptake measures are more feasible and may better predict clinical cardiac outcomes than maximal tests in older adults with heart failure (HF). We examined relationships between maximal oxygen uptake, submaximal oxygen kinetics, functional mobility, and physical activity in older adults with HF and reduced ejection fraction. Older adults with HF and reduced ejection fraction (n = 25, age 75 ± 7 years) were compared to 25 healthy age- and gender-matched controls. Assessments included a maximal treadmill test for peak oxygen uptake (VO2peak), oxygen uptake kinetics at onset of and on recovery from a submaximal treadmill test, functional mobility testing [Get Up and Go (GUG), Comfortable Gait Speed (CGS), Unipedal Stance (US)], and self-reported physical activity (PA). Compared to controls, HF had worse performance on GUG, CGS, and US, greater delays in submaximal oxygen uptake kinetics, and lower PA. In controls, VO2peak was more strongly associated with functional mobility and PA than submaximal oxygen uptake kinetics. In HF patients, submaximal oxygen uptake kinetics were similarly associated with GUG and CGS as VO2peak, but weakly associated with PA. Based on their mobility performance, older HF patients with reduced ejection fraction are at risk for adverse functional outcomes. In this population, submaximal oxygen uptake measures may be equivalent to VO2 peak in predicting functional mobility, and in addition to being more feasible, may provide better insight into how aerobic function relates to mobility in older adults with HF.

Balancing the competing requirements of air-breathing and display behaviour during male-male interactions in Siamese fighting fish Betta splendens.

PubMed

Alton, Lesley A; Portugal, Steven J; White, Craig R

2013-02-01

Air-breathing fish of the Anabantoidei group meet their metabolic requirements for oxygen through both aerial and aquatic gas exchange. Siamese fighting fish Betta splendens are anabantoids that frequently engage in aggressive male-male interactions which cause significant increases in metabolic rate and oxygen requirements. These interactions involve opercular flaring behaviour that is thought to limit aquatic oxygen uptake, and combines with the increase in metabolic rate to cause an increase in air-breathing behaviour. Air-breathing events interrupt display behaviour and increase risk of predation, raising the question of how Siamese fighting fish manage their oxygen requirements during agonistic encounters. Using open-flow respirometry, we measured rate of oxygen consumption in displaying fish to determine if males increase oxygen uptake per breath to minimise visits to the surface, or increase their reliance on aquatic oxygen uptake. We found that the increased oxygen requirements of Siamese fighting fish during display behaviour were met by increased oxygen uptake from the air with no significant changes in aquatic oxygen uptake. The increased aerial oxygen uptake was achieved almost entirely by an increase in air-breathing frequency. We conclude that limitations imposed by the reduced gill surface area of air-breathing fish restrict the ability of Siamese fighting fish to increase aquatic uptake, and limitations of the air-breathing organ of anabantoids largely restrict their capacity to increase oxygen uptake per breath. The resulting need to increase surfacing frequency during metabolically demanding agonistic encounters has presumably contributed to the evolution of the stereotyped surfacing behaviour seen during male-male interactions, during which one of the fish will lead the other to the surface, and each will take a breath of air. Copyright © 2012. Published by Elsevier Inc.

Is the 6-minute walk test a reliable substitute for peak oxygen uptake in patients with dilated cardiomyopathy?

PubMed

Zugck, C; Krüger, C; Dürr, S; Gerber, S H; Haunstetter, A; Hornig, K; Kübler, W; Haass, M

2000-04-01

The 6-min walk test may serve as a more simple clinical tool to assess functional capacity in congestive heart failure than determination of peak oxygen uptake by cardiopulmonary exercise testing. The purpose of the study was to prospectively examine whether the distance ambulated during a 6-min walk test (i) correlates with peak oxygen uptake, (ii) allows peak oxygen uptake to be predicted, and (iii) provides prognostic information similar to peak oxygen uptake in patients with dilated cardiomyopathy and left ventricular ejection fraction < or = 35%. In 113 patients (age: 54+/-12 years, NYHA: 2.2+/-0.8) with dilated cardiomyopathy (left ventricular ejection fraction 19+/-7%) a 6-min walk test and cardiopulmonary exercise testing were performed. The 6-min walk test and peak oxygen uptake were closely correlated at the initial visit (r=0.68, n=113), as well as after 263+/-114 (r=0.71, n=28) and 381+/-170 days (r=0.74, n=14). During serial exercise testing the 6-min walk test allowed peak oxygen uptake to be reliably predicted (r=0.76 between calculated and real peak oxygen uptake). After 528+/-234 days, 42 patients were hospitalized due to worsening heart failure and/or died from cardiovascular causes. Compared to clinically stable patients, these 42 patients walked a shorter distance (423+/-104 vs 501+/-95 m, P<0.001) and had a lower peak oxygen uptake (12.7+/-4.0 vs 17.4 + 5.6 ml x min(-1) x kg(-1), P<0.001). By univariate analysis the 6-min walk test outperformed other prognostic parameters such as left ventricular ejection fraction, cardiac index and plasma norepinephrine concentration and conferred a prognostic power similar to peak oxygen uptake. This predictive value could be further improved in a multivariate model, by combining the 6-min walk test with independent variables, such as left ventricular ejection fraction or cardiac index. The 6-min walk test correlated with peak oxygen uptake when tested serially over the course of the disease. Although both tests define two distinct domains of functional capacity, the 6-min walk test provides prognostic information very similar to peak oxygen uptake in congestive heart failure patients with dilated cardiomyopathy.

The contribution of water soluble and water insoluble organic fractions to oxygen uptake rate during high rate composting.

PubMed

Giuliana, D'Imporzano; Fabrizio, Adani

2007-02-01

This study aims to establish the contribution of the water soluble and water insoluble organic fractions to total oxygen uptake rate during high rate composting process of a mixture of organic fraction of municipal solid waste and lignocellulosic material. This mixture was composted using a 20 l self-heating pilot scale composter for 250 h. The composter was fully equipped to record both the biomass-temperature and oxygen uptake rate. Representative compost samples were taken at 0, 70, 100, 110, 160, and 250 h from starting time. Compost samples were fractionated in water soluble and water insoluble fractions. The water soluble fraction was then fractionated in hydrophilic, hydrophobic, and neutral hydrophobic fractions. Each fraction was then studied using quantitative (total organic carbon) and qualitative analysis (diffuse reflectance infrared spectroscopy and biodegradability test). Oxygen uptake rates were high during the initial stages of the process due to rapid degradation of the soluble degradable organic fraction (hydrophilic plus hydrophobic fractions). Once this fraction was depleted, polymer hydrolysis accounted for most of the oxygen uptake rate. Finally, oxygen uptake rate could be modeled using a two term kinetic. The first term provides the oxygen uptake rate resulting from the microbial growth kinetic type on easily available, no-limiting substrate (soluble fraction), while the second term considers the oxygen uptake rate caused by the degradation of substrate produced by polymer hydrolysis.

Prognostic value of the oxygen uptake efficiency slope and other exercise variables in patients with coronary artery disease.

PubMed

Coeckelberghs, Ellen; Buys, Roselien; Goetschalckx, Kaatje; Cornelissen, Véronique A; Vanhees, Luc

2016-02-01

Peak exercise capacity is an independent predictor for mortality in patients with coronary artery disease. However, sometimes cardiopulmonary exercise tests are stopped prematurely. Therefore, submaximal exercise measures such as the oxygen uptake efficiency slope have been introduced. The aim of this study was to assess the prognostic value of the oxygen uptake efficiency slope and other exercise parameters, in patients with coronary artery disease. Between 2000 and 2011, 1409 patients with coronary artery disease (age 60.7 ± 9.9 years; 1205 males) underwent cardiopulmonary exercise tests. A maximal effort was not reached in 161 (11.5%) patients. The oxygen uptake efficiency slope was calculated and information on mortality was obtained. Cox proportional hazards regression analyses were used to assess the relation of oxygen uptake efficiency slope and other gas exchange variables with all-cause and cardiovascular mortality. Receiver operating characteristic curve analyses was performed to define optimal cut-off values. During an average follow-up of 7.45 ± 3.20 years (range 0.16-13.95 years), 158 patients died, among which 68 patients for cardiovascular reasons. The oxygen uptake efficiency slope was related to all-cause (hazard ratio: 0.568, p < 0.001) and cardiovascular (hazard ratio: 0.461, p < 0.001) mortality. When significant covariates were entered in the analysis, oxygen uptake efficiency slope remained related to mortality (p < 0.05). When other submaximal exercise parameters were added to the model, oxygen uptake efficiency slope and minute ventilation/carbon dioxide production slope also remained significantly related to mortality. The oxygen uptake efficiency slope is an independent predictor for all-cause and cardiovascular mortality in patients with coronary artery disease, irrespective of a truly maximal effort during cardiopulmonary exercise tests. Furthermore, the oxygen uptake efficiency slope provides prognostic information, complementary to the minute ventilation/carbon dioxide production slope and peak exercise capacity. © The European Society of Cardiology 2015.

Peak oxygen uptake in a sprint interval testing protocol vs. maximal oxygen uptake in an incremental testing protocol and their relationship with cross-country mountain biking performance.

PubMed

Hebisz, Rafał; Hebisz, Paulina; Zatoń, Marek; Michalik, Kamil

2017-04-01

In the literature, the exercise capacity of cyclists is typically assessed using incremental and endurance exercise tests. The aim of the present study was to confirm whether peak oxygen uptake (V̇O 2peak ) attained in a sprint interval testing protocol correlates with cycling performance, and whether it corresponds to maximal oxygen uptake (V̇O 2max ) determined by an incremental testing protocol. A sample of 28 trained mountain bike cyclists executed 3 performance tests: (i) incremental testing protocol (ITP) in which the participant cycled to volitional exhaustion, (ii) sprint interval testing protocol (SITP) composed of four 30 s maximal intensity cycling bouts interspersed with 90 s recovery periods, (iii) competition in a simulated mountain biking race. Oxygen uptake, pulmonary ventilation, work, and power output were measured during the ITP and SITP with postexercise blood lactate and hydrogen ion concentrations collected. Race times were recorded. No significant inter-individual differences were observed in regards to any of the ITP-associated variables. However, 9 individuals presented significantly increased oxygen uptake, pulmonary ventilation, and work output in the SITP compared with the remaining cyclists. In addition, in this group of 9 cyclists, oxygen uptake in SITP was significantly higher than in ITP. After the simulated race, this group of 9 cyclists achieved significantly better competition times (99.5 ± 5.2 min) than the other cyclists (110.5 ± 6.7 min). We conclude that mountain bike cyclists who demonstrate higher peak oxygen uptake in a sprint interval testing protocol than maximal oxygen uptake attained in an incremental testing protocol demonstrate superior competitive performance.

The Effects of Capillary Transit Time Heterogeneity (CTH) on the Cerebral Uptake of Glucose and Glucose Analogs: Application to FDG and Comparison to Oxygen Uptake

PubMed Central

Angleys, Hugo; Jespersen, Sune N.; Østergaard, Leif

2016-01-01

Glucose is the brain's principal source of ATP, but the extent to which cerebral glucose consumption (CMRglc) is coupled with its oxygen consumption (CMRO2) remains unclear. Measurements of the brain's oxygen-glucose index OGI = CMRO2/CMRglc suggest that its oxygen uptake largely suffices for oxidative phosphorylation. Nevertheless, during functional activation and in some disease states, brain tissue seemingly produces lactate although cerebral blood flow (CBF) delivers sufficient oxygen, so-called aerobic glycolysis. OGI measurements, in turn, are method-dependent in that estimates based on glucose analog uptake depend on the so-called lumped constant (LC) to arrive at CMRglc. Capillary transit time heterogeneity (CTH), which is believed to change during functional activation and in some disease states, affects the extraction efficacy of oxygen from blood. We developed a three-compartment model of glucose extraction to examine whether CTH also affects glucose extraction into brain tissue. We then combined this model with our previous model of oxygen extraction to examine whether differential glucose and oxygen extraction might favor non-oxidative glucose metabolism under certain conditions. Our model predicts that glucose uptake is largely unaffected by changes in its plasma concentration, while changes in CBF and CTH affect glucose and oxygen uptake to different extents. Accordingly, functional hyperemia facilitates glucose uptake more than oxygen uptake, favoring aerobic glycolysis during enhanced energy demands. Applying our model to glucose analogs, we observe that LC depends on physiological state, with a risk of overestimating relative increases in CMRglc during functional activation by as much as 50%. PMID:27790110

Thromboxane plays a role in postprandial jejunal oxygen uptake and capillary exchange.

PubMed

Alemayehu, A; Chou, C C

1990-09-01

The effects of a thromboxane A2 (TxA2)-endoperoxide receptor antagonist, SQ 29548, on jejunal blood flow, oxygen uptake, and capillary filtration coefficient (Kfc) were determined in anesthetized dogs under resting conditions and during the presence of predigested food in the jejunal lumen in three series of experiments. In series 1, 2.0 micrograms intra-arterial administration of SQ 29548 was found to abolish completely the vasoconstrictor action of graded doses (0.05-2.0 micrograms) of intra-arterial injection of a TxA2-endoperoxide analogue, U44069. SQ 29548 (2.0 micrograms ia) per se did not significantly alter resting jejunal blood flow, oxygen uptake, capillary pressure, or Kfc. Before SQ 29548, placement of food plus bile into the jejunal lumen increased blood flow +42 +/- 9%, oxygen uptake +28 +/- 7%, and Kfc +24 +/- 6%. After SQ 29548, the food placement increased blood flow +37 +/- 8%, oxygen uptake +52 +/- 11%, and Kfc +63 +/- 20%. The food-induced increases in oxygen uptake and Kfc after SQ 29548 were significantly greater than those induced before the blocking of TxA2-endoperoxide receptors by SQ 29548. Our study indicates that endogenous thromboxane does not play a role in regulating jejunal blood flow, capillary filtration, and oxygen uptake under resting conditions. However, it plays a role in limiting the food-induced increases in jejunal oxygen uptake and capillary exchange capacity without influencing the food-induced hyperemia.

Within-session responses to high-intensity interval training in spinal cord injury.

PubMed

Astorino, Todd Anthony; Thum, Jacob S

2018-02-01

Completion of high-intensity interval training (HIIT) increases maximal oxygen uptake and health status, yet its feasibility in persons with spinal cord injury is unknown. To compare changes in cardiorespiratory and metabolic variables between two interval training regimes and moderate intensity exercise. Nine adults with spinal cord injury (duration = 6.8 ± 6.2 year) initially underwent determination of peak oxygen uptake. During subsequent sessions, they completed moderate intensity exercise, HIIT, or sprint interval training. Oxygen uptake, heart rate, and blood lactate concentration were measured. Oxygen uptake and heart rate increased (p < 0.05) during both interval training sessions and were similar (p > 0.05) to moderate intensity exercise. Peak oxygen uptake and heart rate were higher (p < 0.05) with HIIT (90% peak oxygen uptake and 99% peak heart rate) and sprint interval training (80% peak oxygen uptake and 96% peak heart rate) versus moderate intensity exercise. Despite a higher intensity and peak cardiorespiratory strain, all participants preferred interval training versus moderate exercise. Examining long-term efficacy and feasibility of interval training in this population is merited, considering that exercise intensity is recognized as the most important variable factor of exercise programming to optimize maximal oxygen uptake. Implications for Rehabilitation Spinal cord injury (SCI) reduces locomotion which impairs voluntary physical activity, typically resulting in a reduction in peak oxygen uptake and enhanced chronic disease risk. In various able-bodied populations, completion of high-intensity interval training (HIIT) has been consistently reported to improve cardiorespiratory fitness and other health-related outcomes, although its efficacy in persons with SCI is poorly understood. Data from this study in 9 men and women with SCI show similar changes in oxygen uptake and heart in response to HIIT compared to a prolonged bout of aerobic exercise, although peak values were higher in response to HIIT. Due to the higher peak metabolic strain induced by HIIT as well as universal preference for this modality versus aerobic exercise as reported in this study, further work testing utility of HIIT in this population is merited.

VO2 kinetics of constant-load exercise following bed-rest-induced deconditioning

NASA Technical Reports Server (NTRS)

Convertino, V. A.; Goldwater, D. J.; Sandler, H.

1984-01-01

Previous studies have shown that the oxygen uptake kinetics during exercise and recovery may be changed by alterations in work intensity, prior exercise, muscle group involvement, ambient conditions, posture, disease state, and level of physical conditioning. However, the effects of detraining on oxygen uptake kinetics have not been determined. The present investigation has the objective to determine the effects of deconditioning following seven days of continuous head-down bed rest on changes in steady-state oxygen uptake, O2 deficit, and recovery oxygen uptake during the performance of constant-load exercise. The obtained results may provide support for previous proposals that submaximal oxygen uptake was significantly reduced following bed rest. The major finding was that bed-rest deconditioning resulted in a reduction of total O2 transport/utilization capacity during the transient phase of upright but not supine exercise.

Modeling the relationship between fluorodeoxyglucose uptake and tumor radioresistance as a function of the tumor microenvironment.

PubMed

Jeong, Jeho; Deasy, Joseph O

2014-01-01

High fluorodeoxyglucose positron emission tomography (FDG-PET) uptake in tumors has often been correlated with increasing local failure and shorter overall survival, but the radiobiological mechanisms of this uptake are unclear. We explore the relationship between FDG-PET uptake and tumor radioresistance using a mechanistic model that considers cellular status as a function of microenvironmental conditions, including proliferating cells with access to oxygen and glucose, metabolically active cells with access to glucose but not oxygen, and severely hypoxic cells that are starving. However, it is unclear what the precise uptake levels of glucose should be for cells that receive oxygen and glucose versus cells that only receive glucose. Different potential FDG uptake profiles, as a function of the microenvironment, were simulated. Predicted tumor doses for 50% control (TD50) in 2 Gy fractions were estimated for each assumed uptake profile and for various possible cell mixtures. The results support the hypothesis of an increased avidity of FDG for cells in the intermediate stress state (those receiving glucose but not oxygen) compared to well-oxygenated (and proliferating) cells.

Blood flow and oxygen uptake during exercise

NASA Technical Reports Server (NTRS)

Mitchell, J. W.; Stolwijk, J. A. J.; Nadel, E. R.

1973-01-01

A model is developed for predicting oxygen uptake, muscle blood flow, and blood chemistry changes under exercise conditions. In this model, the working muscle mass system is analyzed. The conservation of matter principle is applied to the oxygen in a unit mass of working muscle under transient exercise conditions. This principle is used to relate the inflow of oxygen carried with the blood to the outflow carried with blood, the rate of change of oxygen stored in the muscle myoglobin, and the uptake by the muscle. Standard blood chemistry relations are incorporated to evaluate venous levels of oxygen, pH, and carbon dioxide.

Optimum aerobic volume control based on continuous in-line oxygen uptake monitoring.

PubMed

Svardal, K; Lindtner, S; Winkler, S

2003-01-01

Dynamic adaptation of the aerated volume to changing load conditions is essential to maximise the nitrogen removal performance and to minimise energy consumption. A control strategy is presented which provides optimum aerobic volume control (OAV-control concept) based on continuous in-line oxygen uptake monitoring. For ammonium concentrations below 1 mg/l the oxygen uptake rate shows a strong and almost linear dependency on the ammonium concentration. Therefore, the oxygen uptake rate is an ideal indicator for the nitrification performance in activated sludge systems. The OAV-control concept provides dynamic variation of the minimum aerobic volume required for complete nitrification and therefore maximises the denitrification performance. In-line oxygen uptake monitoring is carried out by controlling the oxygen concentration in a continuous aerated zone of the aeration tank and measuring the total air flow to the aeration tank. The total air flow to the aeration tank is directly proportional to the current oxygen uptake rate and can therefore be used as an indicator for the required aerobic volume. The instrumentation requirements for installation of the OAV-control are relatively low, oxygen sensors in the aeration tank and an on-line air flow measurement are needed. This enables individual control of aeration tanks operated in parallel at low investment costs. The OAV-control concept is installed at the WWTP Linz-Asten (1 Mio PE) and shows very good results. Full scale results are presented.

The Education and Evaluation of Vitamin Consumption Effects on Stress Markers Oxidative after Exercise

ERIC Educational Resources Information Center

Sam, Cemil Tugrulhan

2015-01-01

The purpose of the research was to evaluate the effect of 4-week vitamin C and E supplementation on the markers of oxidative stress after exercise session in students. 30 non-athlete persons (25.21 ± 1.5 years, 173.42 ± 5.62 cm, 75.6±5.75 kg, VO[subscript 2] max of 42.26 ± 1.11 ml/kg/min, and waist-hip ratio of 0.91 ±0.02 cm) volunteered for the…

Influence of protein ingestion on human splanchnic and whole-body oxygen consumption, blood flow, and blood temperature.

PubMed

Brundin, T; Wahren, J

1994-05-01

Splanchnic and whole-body oxygen uptake, blood flow, and blood temperature were studied in 10 healthy subjects before and during 2 hours after oral ingestion of 900 kJ of fish protein. Indirect calorimetry and catheter techniques were used, including blood thermometry in arterial, pulmonary arterial, and hepatic venous blood. After the meal, pulmonary oxygen uptake increased from a basal value of 272 +/- 11 to 332 +/- 23 mL/min. During the first postprandial hour, splanchnic oxygen uptake increased from 62 +/- 5 to 93 +/- 9 mL/min (+50%, P < .05), thereby accounting for 62% +/- 17% of the simultaneous increase in whole-body oxygen consumption. During the second postprandial hour, splanchnic oxygen uptake increased no further, whereas in the extrasplanchnic tissues the oxygen consumption increased, now accounting for the entire simultaneous increase in pulmonary oxygen uptake. Cardiac output increased from basal 6.4 +/- 0.4 to 7.5 +/- 0.5 L/min. Splanchnic blood flow changed little while the arteriohepatic venous oxygen difference increased from 46 +/- 3 to 54 +/- 4 mL/L. Arterial and hepatic venous blood temperatures increased by almost 0.3 degrees C, reflecting a considerable accumulation of heat, indicating a conversion into a positive thermal balance. It is concluded that after protein ingestion, (1) oxygen uptake increases mainly in the splanchnic organs during the first hour, and thereafter exclusively in the extrasplanchnic tissues; (2) the blood flow increases mainly in extrasplanchnic tissues; and (3) the blood temperature increases almost linearly, indicating an upward adjustment of the temperature setpoint in the central thermosensors.

In vivo aerobic metabolism of the rainbow trout gut and the effects of an acute temperature increase and stress event.

PubMed

Brijs, Jeroen; Gräns, Albin; Hjelmstedt, Per; Sandblom, Erik; van Nuland, Nicole; Berg, Charlotte; Axelsson, Michael

2018-05-24

The fish gut is responsible for numerous potentially energetically costly processes, yet, little is known about its metabolism. Here, we provide the first in vivo measurements for aerobic metabolism of the gut in a teleost fish by measuring gut blood flow, as well as arterial and portal venous oxygen content. At 10°C, gut oxygen uptake rates were 4.3±0.5 ml O 2 h -1 kg -1 (∼11% of whole animal oxygen uptake). Following acute warming to 15°C, gut blood flow increased ∼3.4-fold and gut oxygen uptake rate increased ∼3.7-fold (16.0±3.3 ml O 2 h -1 kg -1 ), now representing ∼25% of whole animal oxygen uptake. Although gut blood flow decreased following an acute stress event at 15°C, gut oxygen uptake remained unchanged due to a ∼2-fold increase in oxygen extraction. The high metabolic thermal sensitivity of the gut discovered here could have important implications on the overall aerobic capacity and performance of fish and warrants further investigations. © 2018. Published by The Company of Biologists Ltd.

Annual variation in condition, respiration and remineralisation of Mytilus edulis L. in the Sound, Denmark

NASA Astrophysics Data System (ADS)

Schlüter, L.; Josefsen, S. B.

1994-12-01

By means of monthly in situ incubations, variations in oxygen uptake, nutrient release and C/N-ratio were monitored during a period of 14 months of a mussel population ( Mytilus edulis L.) located on an exposed beach. A condition index calculated as weight/length3 showed that the condition of the mussels was highest in the spring. Specific oxygen uptake and nutrient release had separate maxima, with high oxygen uptake in the spring coinciding with a period of growth, and high nutrient release during summer when the temperature was highest. Oxygen uptake was significantly correlated with both the condition of the mussels and the temperature, while ammonium release was significantly correlated only with the temperature. Except in spring, the oxygen uptake, condition index and O/N-ratio were low, indicating a poor condition of the mussels. The mussels suffered from suboptimal conditions caused by inadequate food supply and failed to accumulate glycogen reserves essential for the development of mature gametes.

Respiratory and digestive responses of postprandial Dungeness crabs, Cancer magister, and blue crabs, Callinectes sapidus, during hyposaline exposure.

PubMed

Curtis, Daniel L; McGaw, Iain J

2010-02-01

Respiratory responses and gastric processing were examined during hyposaline exposure in two crab species of differing osmoregulatory ability. The efficient osmoregulator, Callinectes sapidus, displayed an immediate increase in oxygen uptake when exposed to low salinity in isolation. In contrast, the weak osmoregulator, Cancer magister, showed no change in oxygen uptake upon acute exposure (<6 h), but slight increases in oxygen uptake tended to occur over longer time scales (12-24 h). These changes were likely attributable to an increase in avoidance activity after 6 h hyposaline exposure. Following feeding in 100% SW, oxygen uptake doubled for both species and remained elevated for 15 h. When postprandial crabs were exposed to low salinities, C. sapidus were able to sum the demands of osmoregulation and digestion. Thus, gastric processes continued unabated in low salinity. Conversely, postprandial C. magister prioritized responses to low salinity over those of digestion, resulting in a decrease in oxygen uptake when exposed to low salinity. This decrease in oxygen uptake corresponded to a reduction in the rate of contraction of the pyloric stomach and a subsequent doubling of gastric evacuation time. The current study is one of the few to illustrate how summation or prioritization of competing physiological systems is manifested in digestive processes.

Increased cardiac output elicits higher V̇O2max in response to self-paced exercise.

PubMed

Astorino, Todd Anthony; McMillan, David William; Edmunds, Ross Montgomery; Sanchez, Eduardo

2015-03-01

Recently, a self-paced protocol demonstrated higher maximal oxygen uptake versus the traditional ramp protocol. The primary aim of the current study was to further explore potential differences in maximal oxygen uptake between the ramp and self-paced protocols using simultaneous measurement of cardiac output. Active men and women of various fitness levels (N = 30, mean age = 26.0 ± 5.0 years) completed 3 graded exercise tests separated by a minimum of 48 h. Participants initially completed progressive ramp exercise to exhaustion to determine maximal oxygen uptake followed by a verification test to confirm maximal oxygen uptake attainment. Over the next 2 sessions, they performed a self-paced and an additional ramp protocol. During exercise, gas exchange data were obtained using indirect calorimetry, and thoracic impedance was utilized to estimate hemodynamic function (stroke volume and cardiac output). One-way ANOVA with repeated measures was used to determine differences in maximal oxygen uptake and cardiac output between ramp and self-paced testing. Results demonstrated lower (p < 0.001) maximal oxygen uptake via the ramp (47.2 ± 10.2 mL·kg(-1)·min(-1)) versus the self-paced (50.2 ± 9.6 mL·kg(-1)·min(-1)) protocol, with no interaction (p = 0.06) seen for fitness level. Maximal heart rate and cardiac output (p = 0.02) were higher in the self-paced protocol versus ramp exercise. In conclusion, data show that the traditional ramp protocol may underestimate maximal oxygen uptake compared with a newly developed self-paced protocol, with a greater cardiac output potentially responsible for this outcome.

Oxygen uptake on-kinetics during six-minute walk test predicts short-term outcomes after off-pump coronary artery bypass surgery.

PubMed

Rocco, Isadora Salvador; Viceconte, Marcela; Pauletti, Hayanne Osiro; Matos-Garcia, Bruna Caroline; Marcondi, Natasha Oliveira; Bublitz, Caroline; Bolzan, Douglas William; Moreira, Rita Simone Lopes; Reis, Michel Silva; Hossne, Nelson Américo; Gomes, Walter José; Arena, Ross; Guizilini, Solange

2017-12-26

We aimed to investigate the ability of oxygen uptake kinetics to predict short-term outcomes after off-pump coronary artery bypass grafting. Fifty-two patients aged 60.9 ± 7.8 years waiting for off-pump coronary artery bypass surgery were evaluated. The 6-min walk test distance was performed pre-operatively, while simultaneously using a portable cardiopulmonary testing device. The transition of oxygen uptake kinetics from rest to exercise was recorded to calculate oxygen uptake kinetics fitting a monoexponential regression model. Oxygen uptake at steady state, constant time, and mean response time corrected by work rate were analysed. Short-term clinical outcomes were evaluated during the early post-operative of off-pump coronary artery bypass surgery. Multivariate analysis showed body mass index, surgery time, and mean response time corrected by work rate as independent predictors for short-term outcomes. The optimal mean response time corrected by work rate cut-off to estimate short-term clinical outcomes was 1.51 × 10 -3  min 2 /ml. Patients with slower mean response time corrected by work rate demonstrated higher rates of hypertension, diabetes, EuroSCOREII, left ventricular dysfunction, and impaired 6-min walk test parameters. The per cent-predicted distance threshold of 66% in the pre-operative was associated with delayed oxygen uptake kinetics. Pre-operative oxygen uptake kinetics during 6-min walk test predicts short-term clinical outcomes after off-pump coronary artery bypass surgery. From a clinically applicable perspective, a threshold of 66% of pre-operative predicted 6-min walk test distance indicated slower kinetics, which leads to longer intensive care unit and post-surgery hospital length of stay. Implications for rehabilitation Coronary artery bypass grafting is a treatment aimed to improve expectancy of life and prevent disability due to the disease progression; The use of pre-operative submaximal functional capacity test enabled the identification of patients with high risk of complications, where patients with delayed oxygen uptake kinetics exhibited worse short-term outcomes; Our findings suggest the importance of the rehabilitation in the pre-operative in order to "pre-habilitate" the patients to the surgical procedure; Faster oxygen uptake on-kinetics could be achieved by improving the oxidative capacity of muscles and cardiovascular conditioning through rehabilitation, adding better results following cardiac surgery.

Maximal Oxygen Uptake, Sweating and Tolerance to Exercise in the Heat

NASA Technical Reports Server (NTRS)

Greenleaf, J. E.; Castle, B. L.; Ruff, W. K.

1972-01-01

The physiological mechanisms that facilitate acute acclimation to heat have not been fully elucidated, but the result is the establishment of a more efficient cardiovascular system to increase heat dissipation via increased sweating that allows the acclimated man to function with a cooler internal environment and to extend his performance. Men in good physical condition with high maximal oxygen uptakes generally acclimate to heat more rapidly and retain it longer than men in poorer condition. Also, upon first exposure trained men tolerate exercise in the heat better than untrained men. Both resting in heat and physical training in a cool environment confer only partial acclimation when first exposed to work in the heat. These observations suggest separate additive stimuli of metabolic heat from exercise and environmental heat to increase sweating during the acclimation process. However, the necessity of utilizing physical exercise during acclimation has been questioned. Bradbury et al. (1964) have concluded exercise has no effect on the course of heat acclimation since increased sweating can be induced by merely heating resting subjects. Preliminary evidence suggests there is a direct relationship between the maximal oxygen uptake and the capacity to maintain thermal regulation, particularly through the control of sweating. Since increased sweating is an important mechanism for the development of heat acclimation, and fit men have high sweat rates, it follows that upon initial exposure to exercise in the heat, men with high maximal oxygen uptakes should exhibit less strain than men with lower maximal oxygen uptakes. The purpose of this study was: (1) to determine if men with higher maximal oxygen uptakes exhibit greater tolerance than men with lower oxygen uptakes during early exposure to exercise in the heat, and (2) to investigate further the mechanism of the relationship between sweating and maximal work capacity.

Delivery Rate Affects Uptake of a Fluorescent Glucose Analog in Murine Metastatic Breast Cancer

PubMed Central

Rajaram, Narasimhan; Frees, Amy E.; Fontanella, Andrew N.; Zhong, Jim; Hansen, Katherine; Dewhirst, Mark W.; Ramanujam, Nirmala

2013-01-01

We demonstrate an optical strategy using intravital microscopy of dorsal skin flap window chamber models to image glucose uptake and vascular oxygenation in vivo. Glucose uptake was imaged using a fluorescent glucose analog, 2-[N-(7-nitrobenz-2-oxa-1,3-diaxol-4-yl)amino]-2-deoxyglucose (2-NBDG). SO2 was imaged using the differential absorption properties of oxygenated [HbO2] and deoxygenated hemoglobin [dHb]. This study was carried out on two sibling murine mammary adenocarcinoma lines, 4T1 and 4T07. 2-NBDG uptake in the 4T1 tumors was lowest when rates of delivery and clearance were lowest, indicating perfusion-limited uptake in poorly oxygenated tumor regions. For increasing rates of delivery that were still lower than the glucose consumption rate (as measured in vitro), both 2-NBDG uptake and the clearance rate from the tumor increased. When the rate of delivery of 2-NBDG exceeded the glucose consumption rate, 2-NBDG uptake decreased with any further increase in rate of delivery, but the clearance rate continued to increase. This inflection point was not observed in the 4T07 tumors due to an absence of low delivery rates close to the glucose consumption rate. In the 4T07 tumors, 2-NBDG uptake increased with increasing rates of delivery at low rates of clearance. Our results demonstrate that 2-NBDG uptake in tumors is influenced by the rates of delivery and clearance of the tracer. The rates of delivery and clearance are, in turn, dependent on vascular oxygenation of the tumors. Knowledge of the kinetics of tracer uptake as well as vascular oxygenation is essential to make an informed assessment of glucose demand of a tumor. PMID:24204635

Toxicokinetics of PAHs in Hexagenia

USGS Publications Warehouse

Stehly, Guy R.; Landrum, Peter F.; Henry, Mary G.; Klemm, C.

1990-01-01

The clearance of oxygen from water is inversely and linearly related to the weight of the mayfly nymphs, but oxygen clearances were always much less than the uptake clearances of the PAHs. The high PAH uptake clearance compared to oxygen clearance implies a greater surface area or efficiency for PAH accumulation from water.

The influence of tumor oxygenation on hypoxia imaging in murine squamous cell carcinoma using [64Cu]Cu-ATSM or [18F]Fluoromisonidazole positron emission tomography.

PubMed

Matsumoto, Ken-Ichiro; Szajek, Lawrence; Krishna, Murali C; Cook, John A; Seidel, Jurgen; Grimes, Kelly; Carson, Joann; Sowers, Anastasia L; English, Sean; Green, Michael V; Bacharach, Stephen L; Eckelman, William C; Mitchell, James B

2007-04-01

[64Cu]Cu(II)-ATSM (64Cu-ATSM) and [18F]-Fluoromisonidazole (18F-FMiso) tumor binding as assessed by positron emisson topography (PET) was used to determine the responsiveness of each probe to modulation in tumor oxygenation levels in the SCCVII tumor model. Animals bearing the SCCVII tumor were injected with 64Cu-ATSM or 18F-FMiso followed by dynamic small animal PET imaging. Animals were imaged with both agents using different inspired oxygen mixtures (air, 10% oxygen, carbogen) which modulated tumor hypoxia as independently assessed by the hypoxia marker pimonidazole. The extent of hypoxia in the SCCVII tumor as monitored by the pimonidazole hypoxia marker was found to be in the following order: 10% oxygen>air>carbogen. Tumor uptake of 64Cu-ATSM could not be changed if the tumor was oxygenated using carbogen inhalation 90 min post-injection suggesting irreversible cellular uptake of the 64Cu-ATSM complex. A small but significant paradoxical increase in 64Cu-ATSM tumor uptake was observed for animals breathing air or carbogen compared to 10% oxygen. There was a positive trend toward 18F-FMiso tumor uptake as a function of changing hypoxia levels in agreement with the pimonidazole data. 64Cu-ATSM tumor uptake was unable to predictably detect changes in varying amounts of hypoxia when oxygenation levels in SCCVII tumors were modulated. 18F-FMiso tumor uptake was more responsive to changing levels of hypoxia. While the mechanism of nitroimidazole binding to hypoxic cells has been extensively studied, the avid binding of Cu-ATSM to tumors may involve other mechanisms independent of hypoxia that warrant further study.

A quantitative model for oxygen uptake and release in a family of hemeproteins.

PubMed

Bustamante, Juan P; Szretter, María E; Sued, Mariela; Martí, Marcelo A; Estrin, Darío A; Boechi, Leonardo

2016-06-15

Hemeproteins have many diverse functions that largely depend on the rate at which they uptake or release small ligands, like oxygen. These proteins have been extensively studied using either simulations or experiments, albeit only qualitatively and one or two proteins at a time. We present a physical-chemical model, which uses data obtained exclusively from computer simulations, to describe the uptake and release of oxygen in a family of hemeproteins, called truncated hemoglobins (trHbs). Through a rigorous statistical analysis we demonstrate that our model successfully recaptures all the reported experimental oxygen association and dissociation kinetic rate constants, thus allowing us to establish the key factors that determine the rates at which these hemeproteins uptake and release oxygen. We found that internal tunnels as well as the distal site water molecules control ligand uptake, whereas oxygen stabilization by distal site residues controls ligand release. Because these rates largely determine the functions of these hemeproteins, these approaches will also be important tools in characterizing the trHbs members with unknown functions. lboechi@ic.fcen.uba.ar Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Spectrophotometric determination of H2O2-generating oxidases using oxyhemoglobin as oxygen donor and indicator.

PubMed

Bârzu, O; Dânşoreanu, M

1980-01-01

1. Spectrophotometric determination of oxygen uptake using oxyhemoglobin as oxygen donor and indicator was used for assay of H2O2-generating oxidases like monoamine oxidase and glucose oxidase. 2. In order to decompose H2O2 formed during the oxygen uptake, catalase and methanol (or ethanol) was added to the respiratory system. At pH values higher than 7.5 the oxydation of deoxygenated hemoglobin to methemoglobin was less than 3%. 2. Oxidases with low Km for oxygen can be assayed using the spectrophotometric method if suitable correction factors are introduced into the calculation of oxygen uptake. The correction factor represents the ratio of the rate of formation (or disappearance) of one of the reactants and the rate of oxyhemoglobin deoxygenation, measured under identical experimental conditions.

[Effects of Triton X-100 on the oxygen uptake rate of photosystem I particles treated at 70 degrees C].

PubMed

Chen, Wei; Yang, Zhen-Le; Li, Liang-Bi; Kuang, Ting-Yun

2005-06-01

The characteristics including oxygen uptake rates, fluorescence spectra and absorption spectra of photosystem I particles with or without Triton-X 100 treatment before or after the incubation at 70 degrees C for 10 min were compared. The oxygen uptake rates of photosystem I particles decreased after being incubated at 70 degrees C for 10 min, which could be recovered by the addition of Triton-X 100. Singlet oxygen was formed when the light-harvesting complex I was separated from the core complex of photosystem I, which resulted in high oxygen uptake rate. There was much difference in the fluorescence spectra of photosystem I particles between photosystem I particles treated with Triton-X 100 after the incubation at 70 degrees C for 10 min or not, which implies the ability of Triton-X 100 to promote the recovery of photosystem I particles after the incubation at 70 degrees C for 10 min.

Oxidative processes in soybean and pea seeds: effect of light, temperature, and water content

NASA Technical Reports Server (NTRS)

Vertucci, C. W.; Leopold, A. C.

1987-01-01

Oxidative processes are probable determinants of longevity of seeds in storage. Measurements of actual oxygen uptake rates were made for soybean and pea seeds as a comparison of short and long lived seeds when light, temperature, and moisture contents were varied. In both peas and soybeans, the oxygen uptake was depressed at low temperatures (<16 degrees C) and low water contents (< 0.25 gram H2O per gram dry weight). Apparent activation energies under these conditions are very high, while apparent activation energies of seeds at higher water contents and at temperatures greater than 22 degrees C are much less. Light enhances the level of oxygen uptake in pea, but reduces the level of oxygen uptake in soybean. The complexities of the interactions of oxygen uptake with environmental conditions in soybean compared to pea suggest that oxidative processes occur in soybean at low water contents, but are essentially absent in pea. It is suggested that the additional oxidative processes in soybean with moisture contents between 0.10 and 0.24 gram per gram may contribute to the poorer longevity of soybean seed compared to pea seed.

Evaluation of Maximal Oxygen Uptake and Submaximal Estimates of VO2max Before, During, and After Long Duration International Space Station Missions

NASA Technical Reports Server (NTRS)

2008-01-01

Evaluation of Maximal Oxygen Uptake and Submaximal Estimates of VO2max Before, During, and After Long Duration International Space Station Missions (VO2max) will document changes in maximum oxygen uptake for crewmembers onboard the International Space Station (ISS) on long-duration missions, greater than 90 days. This investigation will establish the characteristics of VO2max during flight and assess the validity of the current methods of tracking aerobic capacity change during and following the ISS missions.

Impact of beta-blockers on cardiopulmonary exercise testing in patients with advanced liver disease.

PubMed

Wallen, M P; Hall, A; Dias, K A; Ramos, J S; Keating, S E; Woodward, A J; Skinner, T L; Macdonald, G A; Arena, R; Coombes, J S

2017-10-01

Patients with advanced liver disease may develop portal hypertension that can result in variceal haemorrhage. Beta-blockers reduce portal pressure and minimise haemorrhage risk. These medications may attenuate measures of cardiopulmonary performance, such as the ventilatory threshold and peak oxygen uptake measured via cardiopulmonary exercise testing. To determine the effect of beta-blockers on cardiopulmonary exercise testing variables in patients with advanced liver disease. This was a cross-sectional analysis of 72 participants who completed a cardiopulmonary exercise test before liver transplantation. All participants remained on their usual beta-blocker dose and timing prior to the test. Variables measured during cardiopulmonary exercise testing included the ventilatory threshold, peak oxygen uptake, heart rate, oxygen pulse, the oxygen uptake efficiency slope and the ventilatory equivalents for carbon dioxide slope. Participants taking beta-blockers (n = 28) had a lower ventilatory threshold (P <.01) and peak oxygen uptake (P = .02), compared to participants not taking beta-blockers. After adjusting for age, the model of end-stage liver-disease score, liver-disease aetiology, presence of refractory ascites and ventilatory threshold remained significantly lower in the beta-blocker group (P = .04). The oxygen uptake efficiency slope was not impacted by beta-blocker use. Ventilatory threshold is reduced in patients with advanced liver disease taking beta-blockers compared to those not taking the medication. This may incorrectly risk stratify patients on beta-blockers and has implications for patient management before and after liver transplantation. The oxygen uptake efficiency slope was not influenced by beta-blockers and may therefore be a better measure of cardiopulmonary performance in this patient population. © 2017 John Wiley & Sons Ltd.

Oxygen Uptake. Operational Control Tests for Wastewater Treatment Facilities. Instructor's Manual [and] Student Workbook.

ERIC Educational Resources Information Center

Wooley, John F.

Biological waste treatment in the activated sludge process is based on the ability of microorganisms to use dissolved oxygen in breaking down soluble organic substances. The oxygen uptake test is a means of measuring the respiration rate of microorganisms in this process. Designed for individuals who have completed National Pollutant Discharge…

An Inexpensive Electrode and Cell for Measurement of Oxygen Uptake in Chemical and Biochemical Systems.

ERIC Educational Resources Information Center

Brunet, Juan E.; And Others

1983-01-01

The continuous measurement of oxygen consumption in an enzymatic reaction is a frequent experimental fact and extremely important in the enzymatic activity of oxygenase. An electrochemical system, based on a polarographic method, has been developed to monitor the oxygen uptake. The system developed and electrode used are described. (JN)

Cardiorespiratory deconditioning with static and dynamic leg exercise during bed rest

NASA Technical Reports Server (NTRS)

Stremel, R. W.; Convertino, V. A.; Bernauer, E. M.; Greenleaf, J. E.

1976-01-01

Results are presented for an experimental study designed to compare the effects of heavy static and dynamic exercise training during 14 days of bed rest on the cardiorespiratory responses to submaximal and maximal exercise performed by seven healthy men aged 19-22 yr. The parameters measured were submaximal and maximal oxygen uptake, minute ventilation, heart rate, and plasma volume. The results indicate that exercise alone during bed rest reduces but does not eliminate the reduction in maximal oxygen uptake. An additional positive hydrostatic effect is therefore necessary to restore maximal oxygen uptake to ambulatory control levels. The greater protective effect of static exercise on maximal oxygen uptake is probably due to a greater hydrostatic component from the isometric muscular contraction. Neither the static nor the dynamic exercise training regimes are found to minimize the changes in all the variables studied, thereby suggesting a combination of static and dynamic exercises.

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. © 2014 The Fisheries Society of the British Isles.

Microrespirometer chamber for determinations of viability in cell and organ cultures.

PubMed Central

Gabridge, M G

1976-01-01

The effects of chemical, physical, and infectious cytotoxic agents on primary and cultured cells were evaluated by measurements of oxygen uptake for various time periods. A newly developed respirometer used a Clark oxygen electrode in a 1.0-ml chamber, with provisions for constant mixing and for temperature control of both the sample and electrode chambers. The device was unique because the electrode and instrumentation were provided by a clinical blood-gas analyzer. Oxygen uptake by blank controls was negligible, whereas cells and tissue consumed oxygen at rates of approximately 1 to 5 mul/h in a dose- and temperature-dependent fashion. Cyanide, heat, and freeze-thaw lysis reduced the oxygen uptake to less than 0.6 mul/mg per h. Infection of trachea organ cultures with Mycoplasma pneumoniae significantly reduced relative ciliary activity, tetrazolium reduction capacity, and oxygen consumption in a coordinated fashion. Images PMID:985826

Blood flow regulation and oxygen uptake during high-intensity forearm exercise.

PubMed

Nyberg, S K; Berg, O K; Helgerud, J; Wang, E

2017-04-01

The vascular strain is very high during heavy handgrip exercise, but the intensity and kinetics to reach peak blood flow, and peak oxygen uptake, are uncertain. We included 9 young (25 ± 2 yr) healthy males to evaluate blood flow and oxygen uptake responses during continuous dynamic handgrip exercise with increasing intensity. Blood flow was measured using Doppler-ultrasound, and venous blood was drawn from a deep forearm vein to determine arteriovenous oxygen difference (a-vO 2diff ) during 6-min bouts of 60, 80, and 100% of maximal work rate (WR max ), respectively. Blood flow and oxygen uptake increased ( P < 0.05) from 60%WR max [557 ± 177(SD) ml/min; 56.0 ± 21.6 ml/min] to 80%WR max (679 ± 190 ml/min; 70.6 ± 24.8 ml/min), but no change was seen from 80%WR max to 100%WR max Blood velocity (49.5 ± 11.5 to 58.1 ± 11.6 cm/s) and brachial diameter (0.49 ± 0.05 to 0.50 ± 0.06 cm) showed concomitant increases ( P < 0.05) with blood flow from 60% to 80%WR max, whereas no differences were observed in a-vO 2diff Shear rate also increased ( P < 0.05) from 60% (822 ± 196 s -1 ) to 80% (951 ± 234 s -1 ) of WR max The mean response time (MRT) was slower ( P < 0.05) for blood flow (60%WR max 50 ± 22 s; 80%WR max 51 ± 20 s; 100%WR max 51 ± 23 s) than a-vO 2diff (60%WR max 29 ± 9 s; 80%WR max 29 ± 5 s; 100%WR max 20 ± 5 s), but not different from oxygen uptake (60%WR max 44 ± 25 s; 80%WR max 43 ± 14 s; 100%WR max 41 ± 32 s). No differences were observed in MRT for blood flow or oxygen uptake with increased exercise intensity. In conclusion, when approaching maximal intensity, oxygen uptake appeared to reach a critical level at ~80% of WR max and be regulated by blood flow. This implies that high, but not maximal, exercise intensity may be an optimal stimulus for shear stress-induced small muscle mass training adaptations. NEW & NOTEWORTHY This study evaluated blood flow regulation and oxygen uptake during small muscle mass forearm exercise with high to maximal intensity. Despite utilizing only a fraction of cardiac output, blood flow reached a plateau at 80% of maximal work rate and regulated peak oxygen uptake. Furthermore, the results revealed that muscle contractions dictated bulk oxygen delivery and yielded three times higher peak blood flow in the relaxation phase compared with mean values. Copyright © 2017 the American Physiological Society.

Influence of simulated weightlessness on maximal oxygen uptake of untrained rats

NASA Technical Reports Server (NTRS)

Overton, J. Michael; Tipton, Charles M.

1987-01-01

The purpose of this study was to determine the effect of hindlimb suspension on maximal oxygen uptake of rodents. Male Sprague-Dawley rats were assigned to head-down (HD) suspension, horizontal (HOZ) suspension, or cage (C) control for 6-9 days. Rats were tested for maximal oxygen uptake before and after surgical instrumentation (Doppler flow probes, carotid and jugular cannulae), and after suspension. Body weight was significantly decreased after suspension in both HD and HOZ groups, but was significantly increased in the C group. Absolute maximal O2 uptake (ml/min) was not different in the C group. However, because of their increased weight, relative maximal O2 uptake (ml/min per kg) was significantly reduced. In contrast, both relative and absolute maximal O2 uptake were significantly lower, following suspension, for the HD and HOZ groups. These preliminary results support the use of hindlimb suspension as an effective model to study the mechanism(s) of cardiovascular deconditioning.

Estimating the effect of burrowing shrimp on deep-sea sediment community oxygen consumption.

PubMed

Leduc, Daniel; Pilditch, Conrad A

2017-01-01

Sediment community oxygen consumption (SCOC) is a proxy for organic matter processing and thus provides a useful proxy of benthic ecosystem function. Oxygen uptake in deep-sea sediments is mainly driven by bacteria, and the direct contribution of benthic macro- and mega-infauna respiration is thought to be relatively modest. However, the main contribution of infaunal organisms to benthic respiration, particularly large burrowing organisms, is likely to be indirect and mainly driven by processes such as feeding and bioturbation that stimulate bacterial metabolism and promote the chemical oxidation of reduced solutes. Here, we estimate the direct and indirect contributions of burrowing shrimp ( Eucalastacus cf. torbeni ) to sediment community oxygen consumption based on incubations of sediment cores from 490 m depth on the continental slope of New Zealand. Results indicate that the presence of one shrimp in the sediment is responsible for an oxygen uptake rate of about 40 µmol d -1 , only 1% of which is estimated to be due to shrimp respiration. We estimate that the presence of ten burrowing shrimp m -2 of seabed would lead to an oxygen uptake comparable to current estimates of macro-infaunal community respiration on Chatham Rise based on allometric equations, and would increase total sediment community oxygen uptake by 14% compared to sediment without shrimp. Our findings suggest that oxygen consumption mediated by burrowing shrimp may be substantial in continental slope ecosystems.

CONTINUOUS, AUTOMATED AND SIMULTANEOUS MEASUREMENT OF OXYGEN UPTAKE AND CARBON DIOXIDE EVOLUTION IN BIOLOGICAL SYSTEMS

EPA Science Inventory

Commercial respirometers are capable of continuously and automatically measuring oxygen uptake in bioreactors. A method for continuously and automatically measuring carbon dioxide evolution can be retrofitted to commercial respirometers. Continuous and automatic measurements of...

Effectiveness of Resistance Circuit-Based Training for Maximum Oxygen Uptake and Upper-Body One-Repetition Maximum Improvements: A Systematic Review and Meta-Analysis.

PubMed

Muñoz-Martínez, Francisco Antonio; Rubio-Arias, Jacobo Á; Ramos-Campo, Domingo Jesús; Alcaraz, Pedro E

2017-12-01

It is well known that concurrent increases in both maximal strength and aerobic capacity are associated with improvements in sports performance as well as overall health. One of the most popular training methods used for achieving these objectives is resistance circuit-based training. The objective of the present systematic review with a meta-analysis was to evaluate published studies that have investigated the effects of resistance circuit-based training on maximum oxygen uptake and one-repetition maximum of the upper-body strength (bench press exercise) in healthy adults. The following electronic databases were searched from January to June 2016: PubMed, Web of Science and Cochrane. Studies were included if they met the following criteria: (1) examined healthy adults aged between 18 and 65 years; (2) met the characteristics of resistance circuit-based training; and (3) analysed the outcome variables of maximum oxygen uptake using a gas analyser and/or one-repetition maximum bench press. Of the 100 articles found from the database search and after all duplicates were removed, eight articles were analysed for maximum oxygen uptake. Of 118 healthy adults who performed resistance circuit-based training, maximum oxygen uptake was evaluated before and after the training programme. Additionally, from the 308 articles found for one-repetition maximum, eight articles were analysed. The bench press one-repetition maximum load, of 237 healthy adults who performed resistance circuit-based training, was evaluated before and after the training programme. Significant increases in maximum oxygen uptake and one-repetition maximum bench press were observed following resistance circuit-based training. Additionally, significant differences in maximum oxygen uptake and one-repetition maximum bench press were found between the resistance circuit-based training and control groups. The meta-analysis showed that resistance circuit-based training, independent of the protocol used in the studies, is effective in increasing maximum oxygen uptake and one-repetition maximum bench press in healthy adults. However, its effect appears to be larger depending on the population and training characteristics. For large effects in maximum oxygen uptake, the programme should include ~14-30 sessions for ~6-12 weeks, with each session lasting at least ~20-30 min, at intensities between ~60 and 90% one-repetition maximum. For large effects in one-repetition maximum bench press, the data indicate that intensity should be ~30-60% one-repetition maximum, with sessions lasting at least ~22.5-60 min. However, the lower participant's baseline fitness level may explain the lighter optimal loads used in the circuit training studies where greater strength gains were reported.

Cardiorespiratory performance during prolonged swimming tests with salmonids: a perspective on temperature effects and potential analytical pitfalls.

PubMed

Farrell, A P

2007-11-29

A prolonged swimming trial is the most common approach in studying steady-state changes in oxygen uptake, cardiac output and tissue oxygen extraction as a function of swimming speed in salmonids. The data generated by these sorts of studies are used here to support the idea that a maximum oxygen uptake is reached during a critical swimming speed test. Maximum oxygen uptake has a temperature optimum. Potential explanations are advanced to explain why maximum aerobic performance falls off at high temperature. The valuable information provided by critical swimming tests can be confounded by non-steady-state swimming behaviours, which typically occur with increasing frequency as salmonids approach fatigue. Two major concerns are noted. Foremost, measurements of oxygen uptake during swimming can considerably underestimate the true cost of transport near critical swimming speed, apparently in a temperature-dependent manner. Second, based on a comparison with voluntary swimming ascents in a raceway, forced swimming trials in a swim tunnel respirometer may underestimate critical swimming speed, possibly because fish in a swim tunnel respirometer are unable to sustain a ground speed.

Dynamics and Thermochemistry of Oxygen Uptake by a Mixed Ce-Pr Oxide

NASA Astrophysics Data System (ADS)

Sinev, M. Yu.; Fattakhova, Z. T.; Bychkov, V. Yu.; Lomonosov, V. I.; Gordienko, Yu. A.

2018-03-01

The dynamics of oxygen uptake by mixed Ce0.55Pr0.45O2-x oxide is studied in a pulsed oxygen supply mode using in situ high-temperature heat flow differential scanning calorimetry. It is stated that the oxidation proceeds in two regimes: a fast one at the beginning of the oxidation process, and a slow one, which is controlled by the diffusion of oxygen through the bulk of the solid at the later stages of the process. Analysis of the shape of calorimetric profiles reveals some processes, accompanied by heat release, that occur in the sample in the absence of oxygen in the gas phase. These could be due to both the redistribution of consumed oxygen in the oxide lattice and the lattice relaxation associated with the transformation of phases with different arrangements of oxygen vacancies in them. The heat effect (which diminishes from 60 to 40 kJ/mol in the course of oxygen uptake) associated with the oxidation of the reduced form of mixed Ce-Pr oxide, corresponds to the oxidation of praseodymium ions from (3+) to (4+).

Quadriceps oxygenation during isometric exercise in sailing.

PubMed

Vogiatzis, I; Tzineris, D; Athanasopoulos, D; Georgiadou, O; Geladas, N

2008-01-01

The aim of the present study was to investigate why blood lactate after prolonged quadriceps contraction during hiking is only marginally increased. Eight sailors performed five 3-min hiking bouts interspersed with 5-s recovery periods. Whole body oxygen uptake, heart rate and lactate were recorded, along with continuous-wave near-infrared spectroscopy measures of quadriceps oxygenation. The time for 50% re-oxygenation was also assessed as an indication of the degree of localized oxygen delivery stress. Hiking elicited a significant (p = 0.001) increase in mean (+/- SD) heart rate (124 +/- 10 beats . min (-1)) which was accompanied by a disproportionately low oxygen uptake (12 +/- 2 ml.kg(-1).min(-1)). Lactate was significantly (p = 0.001) increased throughout hiking manoeuvres, though post-exercise it remained low (3.2 +/- 0.9 mmol.l(-1)). During the hiking bouts mean quadriceps oxygenation was significantly (p = 0.001) reduced compared to baseline (by 33 +/- 5%), indicating an imbalance between muscle oxygen accessibility and oxygen demand. During rest intervals quadriceps oxygenation was partially restored. After the end of the final bout the time for 50 % re-oxygenation was only 8 +/- 2 s, whereas recovery of quadriceps oxygenation and oxygen uptake was completed within 3 min. We conclude that the observed low lactate could be attributed to the small oxygen and energy deficits during hiking as the muscles' oxygen accessibility is presumably partially restored during the brief rest intervals.

Gaseous oxygen uptake in porous media at different moisture contents and airflow velocities.

PubMed

Sharma, Prabhakar; Poulsen, Tjalfe G; Kalluri, Prasad N V

2009-06-01

The presence and distribution of water in the pore space is a critical factor for flow and transport of gases through unsaturated porous media. The water content also affects the biological activity necessary for treatment of polluted gas streams in biofilters. In this research, microbial activity and quantity of inactive volume in a porous medium as a function of moisture content and gas flow rate were investigated. Yard waste compost was used as a test medium, and oxygen uptake rate measurements were used to quantify microbial activity and effective active compost volume using batch and column flow-through systems. Compost water contents were varied from air-dry to field capacity and gas flows ranged from 0.2 to 2 L x min(-1). The results showed that overall microbial activity and the relative fraction of active compost medium volume increased with airflow velocity for all levels of water content up to a certain flow rate above which the oxygen uptake rate assumed a constant value independent of gas flow. The actual value of the maximum oxygen uptake rate was controlled by the water content. The oxygen uptake rate also increased with increasing water content and reached a maximum between 42 and 48% volumetric water content, above which it decreased, again likely because of formation of inactive zones in the compost medium. Overall, maximum possible oxygen uptake rate as a function of gas flow rate across all water contents and gas flows could be approximated by a linear expression. The relative fraction of active volume also increased with gas flow rate and reached approximately 80% for the highest gas flows used.

The role of exercise testing in heart failure.

PubMed

Swedberg, K; Gundersen, T

1993-01-01

The objectives of exercise testing in congestive heart failure (CHF) may be summarized as follows: (a) detect impaired cardiac performance, (b) grade severity of cardiac failure and classify functional capability, and (c) assess effects of interventions. Several different methods are available to make these assessments, and we have to ask ourselves how well exercise testing achieves these objectives. It has to be kept in mind that the power generated by the exercising muscles is dependent on the oxygen delivery to the skeletal muscles. Oxygen uptake is the result of an integrated performance of the lungs, heart, and peripheral circulation. In patients, as well as in normal subjects, oxygen uptake is related to hemodynamic indices such as cardiac output, stroke volume, or exercise duration when a stepwise regulated maximal exercise protocol is used. However, there are major differences in the concept of a true maximum in normal subjects versus heart failure patients. Fit-normal subjects will achieve a real maximal oxygen uptake, whereas patients may stop testing before a maximum is reached because of symptoms such as dyspnea or leg fatigue. Therefore, it is better if the actual oxygen uptake can be measured. "Peak" rather than true maximal oxygen uptake has been suggested for the classification of the severity of heart failure. Peripheral factors modify the cardiac output through such factors as vascular resistance, organ function, and hormonal release. Maximal exercise will stress the cardiovascular system to a point where the weakest chain will impose a limiting effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Determinants of maximal oxygen uptake (VO2 max) in fire fighter testing.

PubMed

Vandersmissen, G J M; Verhoogen, R A J R; Van Cauwenbergh, A F M; Godderis, L

2014-07-01

The aim of this study was to evaluate current daily practice of aerobic capacity testing in Belgian fire fighters. The impact of personal and test-related parameters on the outcome has been evaluated. Maximal oxygen uptake (VO2 max) results of 605 male fire fighters gathered between 1999 and 2010 were analysed. The maximal cardio respiratory exercise tests were performed at 22 different centres using different types of tests (tread mill or bicycle), different exercise protocols and measuring equipment. Mean VO2 max was 43.3 (SD = 9.8) ml/kg.min. Besides waist circumference and age, the type of test, the degree of performance of the test and the test centre were statistically significant determinants of maximal oxygen uptake. Test-related parameters have to be taken into account when interpreting and comparing maximal oxygen uptake tests of fire fighters. It highlights the need for standardization of aerobic capacity testing in the medical evaluation of fire fighters. Copyright © 2014 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Fluid-electrolyte shifts and maximal oxygen uptake in man at simulated altitude /2,287 m/

NASA Technical Reports Server (NTRS)

Greenleaf, J. E.; Bernauer, E. M.; Adams, W. C.; Juhos, L.

1978-01-01

Experiments were conducted on six trained distance runners (21-23 yr) subjected to an eight-day dietary control at sea level, followed by an eight-day stay in an altitude chamber (2287-m altitude) and a four-day recovery at sea level. Fluid and electrolyte shifts during exercise at altitude were evaluated to gain insight into the mechanism of reduction in working capacity. The results are discussed in terms of resting fluid volumes and blood constituents, maximal exercise variables, and maximal exercise fluid-electrolyte shifts. Since there are no significant changes in fluid balance or resting plasma volume (PV) at altitude, it is concluded that neither these nor the excessive PV shifts with exercise contribute to the reduction in maximal oxygen uptake at altitude. During altitude exposure the percent loss in PV is found to follow the percent reduction in maximal oxygen uptake; however, on the first day of recovery the percent change in PV remains depressed while maximal oxygen uptake returns to control levels.

Nonoxidative Glucose Consumption during Focal Physiologic Neural Activity

NASA Astrophysics Data System (ADS)

Fox, Peter T.; Raichle, Marcus E.; Mintun, Mark A.; Dence, Carmen

1988-07-01

Brain glucose uptake, oxygen metabolism, and blood flow in humans were measured with positron emission tomography, and a resting-state molar ratio of oxygen to glucose consumption of 4.1:1 was obtained. Physiological neural activity, however, increased glucose uptake and blood flow much more (51 and 50 percent, respectively) than oxygen consumption (5 percent) and produced a molar ratio for the increases of 0.4:1. Transient increases in neural activity cause a tissue uptake of glucose in excess of that consumed by oxidative metabolism, acutely consume much less energy than previously believed, and regulate local blood flow for purposes other than oxidative metabolism.

Parmitano in Columbus module during Oxygen Uptake measurement session

NASA Image and Video Library

2013-10-02

ISS037-E-004950 (2 Oct. 2013) --- European Space Agency astronaut Luca Parmitano, Expedition 37 flight engineer, performs an oxygen uptake measurement session in the Columbus laboratory of the International Space Station. He is wearing a Pulmonary Function System (PFS) face mask during the session.

All puffed out: do pufferfish hold their breath while inflated?

PubMed Central

McGee, Georgia Evelyn; Clark, Timothy Darren

2014-01-01

The inflation response of pufferfishes is one of the most iconic predator defence strategies in nature. Current dogma suggests that pufferfish inflation represents a breath-holding response, whereby gill oxygen uptake ceases for the duration of inflation and cutaneous respiration increases to compensate. Here, we show that the black-saddled pufferfish (Canthigaster valentini) has an excellent capacity for oxygen uptake while inflated, with uptake rates increasing to five-times that of resting levels. Moreover, we show that this species has negligible capacity for cutaneous respiration, concluding that the gills are the primary site of oxygen uptake while inflated. Despite this, post-deflation recovery of aerobic metabolism took an average of 5.6 h, suggesting a contribution of anaerobic metabolism during pre-inflation activity and during the act of ingesting water to achieve inflation. PMID:25472941

VO2 Off Transient Kinetics in Extreme Intensity Swimming.

PubMed

Sousa, Ana; Figueiredo, Pedro; Keskinen, Kari L; Rodríguez, Ferran A; Machado, Leandro; Vilas-Boas, João P; Fernandes, Ricardo J

2011-01-01

Inconsistencies about dynamic asymmetry between the on- and off- transient responses in oxygen uptake are found in the literature. Therefore, the purpose of this study was to characterize the oxygen uptake off-transient kinetics during a maximal 200-m front crawl effort, as examining the degree to which the on/off regularity of the oxygen uptake kinetics response was preserved. Eight high level male swimmers performed a 200-m front crawl at maximal speed during which oxygen uptake was directly measured through breath-by-breath oxymetry (averaged every 5 s). This apparatus was connected to the swimmer by a low hydrodynamic resistance respiratory snorkel and valve system. The on- and off-transient phases were symmetrical in shape (mirror image) once they were adequately fitted by a single-exponential regression models, and no slow component for the oxygen uptake response was developed. Mean (± SD) peak oxygen uptake was 69.0 (± 6.3) mL·kg(-1)·min(-1), significantly correlated with time constant of the off- transient period (r = 0.76, p < 0.05) but not with any of the other oxygen off-transient kinetic parameters studied. A direct relationship between time constant of the off-transient period and mean swimming speed of the 200-m (r = 0.77, p < 0.05), and with the amplitude of the fast component of the effort period (r = 0.72, p < 0.05) were observed. The mean amplitude and time constant of the off-transient period values were significantly greater than the respective on- transient. In conclusion, although an asymmetry between the on- and off kinetic parameters was verified, both the 200-m effort and the respectively recovery period were better characterized by a single exponential regression model. Key pointsThe VO2 slow component was not observed in the recovery period of swimming extreme efforts;The on and off transient periods were better fitted by a single exponential function, and so, these effort and recovery periods of swimming extreme efforts are symmetrical;The rate of VO2 decline during the recovery period may be due to not only the magnitude of oxygen debt but also the VO2peak obtained during the effort period.

Alterations in Strength and Maximal Oxygen Uptake Consequent to Nautilus Circuit Weight Training.

ERIC Educational Resources Information Center

Messier, Stephen P.; Dill, Mary Elizabeth

1985-01-01

The study compared the effects on muscular strength and maximal oxygen uptake of a Nautilus circuit weight training program, a free weight strength training program, and a running program. Nautilus circuit weight training appears to be equally effective for a training period of short duration. (MT)

Maximum Oxygen Uptake Determination in Insulin-Dependent Diabetes Mellitus.

ERIC Educational Resources Information Center

Fremion, Amy S.; And Others

1987-01-01

A study of 10 children with insulin-dependent diabetes mellitus performing a maximum-effort cycling test indicated blood glucose levels did not change appreciably during test, while maximal oxygen uptake was substandard for their age groups. Findings suggest patients in fair to poor metabolic control can tolerate stress testing without…

Relationship between oxygen cost of walking and level of walking disability after stroke: An experimental study.

PubMed

Polese, Janaine C; Ada, Louise; Teixeira-Salmela, Luci F

2018-01-01

Since physical inactivity is the major risk factor for recurrent stroke, it is important to understand how level of disability impacts oxygen uptake by people after stroke. This study investigated the nature of the relationship between level of disability and oxygen cost in people with chronic stroke. Level of walking disability was measured as comfortable walking speed using the 10-m Walk Test reported in m/s with 55 ambulatory people 2 years after stroke. Oxygen cost was measured during 3 walking tasks: overground walking at comfortable speed, overground walking at fast speed, and stair walking at comfortable speed. Oxygen cost was calculated from oxygen uptake divided by distance covered during walking and reported in ml∙kg -1 ∙m -1 . The relationship between level of walking disability and oxygen cost was curvilinear for all 3 walking tasks. One quadratic model accounted for 81% (95% CI [74, 88]) of the variance in oxygen cost during the 3 walking tasks: [Formula: see text] DISCUSSION: The oxygen cost of walking was related the level of walking disability in people with chronic stroke, such that the more disabled the individual, the higher the oxygen cost of walking; with oxygen cost rising sharply as disability became severe. An equation that relates oxygen cost during different walking tasks according to the level of walking disability allows clinicians to determine oxygen cost indirectly without the difficulty of measuring oxygen uptake directly. Copyright © 2017 John Wiley & Sons, Ltd.

Peripheral circulatory responses in vivo from regional brachial biceps and lumbar muscles in healthy men and women during pushing and pulling exercise.

PubMed

Maikala, Rammohan V; Bhambhani, Yagesh N

2007-06-01

Although women have been performing increasingly more manual labor in the workplace in the past 2 decades, their physiological responses and gender-based differences in muscle microvascularity during occupational activities have not yet been extensively documented. This study assessed gender differences and tissue heterogeneity in peripheral circulatory responses from 2 muscle groups during pushing and pulling exercise until volitional exhaustion. In healthy men and women, near-infrared spectroscopy was used to determine peripheral responses, oxygenation, and blood volume simultaneously from the right biceps brachii and lumbar erector spinae. Pulmonary oxygen uptake was assessed using a metabolic measurement cart. Although the 11 men who participated in the study demonstrated greater pulmonary oxygen uptake and power output at volitional exhaustion, their peak peripheral responses for both muscles were similar to those of the 11 women participating. In both sexes, oxygenations trends decreased in both muscles with an increase in workload. However, whereas blood volume increased in the biceps, it decreased in the lumbar muscle in both sexes. At 20% to 60% levels of peak pulmonary oxygen uptake, the percent change in peripheral bicep responses was greater for men than for women (P < 0.05). In contrast, women demonstrated greater change in lumbar muscle oxygenation compared with men at 40% to 60% of peak pulmonary oxygen uptake (P < 0.05). Similar peripheral responses for biceps and lumbar muscles at the point of volitional exhaustion suggest that gender differences in pulmonary oxygen uptake are independent of oxygen extraction or delivery across the muscle groups monitored. However, at submaximal levels of exercise, the peripheral changes in each muscle were gender dependent. Although biceps and lumbar muscles are 2 discrete muscle groups, based on the heterogeneity found in the blood volume trends it is likely that oxygen supply and demand are regulated by muscle location and muscle fiber characteristics. Overall, gender-based assessment of occupational activities should incorporate both pulmonary and peripheral circulatory responses to understand each sex's performance effectiveness.

Taking their breath away: metabolic responses to low-oxygen levels in anchialine shrimps (Crustacea: Atyidae and Alpheidae).

PubMed

Havird, Justin C; Vaught, Rebecca C; Weeks, Jeffrey R; Fujita, Yoshihisa; Hidaka, Michio; Santos, Scott R; Henry, Raymond P

2014-12-01

Crustaceans generally act as oxy-regulators, maintaining constant oxygen uptake as oxygen partial pressures decrease, but when a critical low level is reached, ventilation and aerobic metabolism shut down. Cave-adapted animals, including crustaceans, often show a reduced metabolic rate possibly owing in part to the hypoxic nature of such environments. However, metabolic rates have not been thoroughly explored in crustaceans from anchialine habitats (coastal ponds and caves), which can experience variable oxygenic regimes. Here, an atypical oxy-conforming pattern of oxygen uptake is reported in the Hawaiian anchialine atyid Halocaridina rubra, along with other unusual metabolic characteristics. Ventilatory rates are near-maximal in normoxia and did not increase appreciably as PO₂ declined, resulting in a decline in VO₂ during progressive hypoxia. Halocaridina rubra maintained in anoxic waters survived for seven days (the duration of the experiment) with no measureable oxygen uptake, suggesting a reliance on anaerobic metabolism. Supporting this, lactate dehydrogenase activity was high, even in normoxia, and oxygen debts were quickly repaid by an unusually extreme increase in oxygen uptake upon exposure to normoxia. In contrast, four related anchialine shrimp species from the Ryukyu Islands, Japan, exhibited physiological properties consistent with previously studied crustaceans. The unusual respiratory patterns found in H. rubra are discussed in the context of a trade-off in gill morphology for osmoregulatory ion transport vs. diffusion of respiratory gasses. Future focus on anchialine species may offer novel insight into the diversity of metabolic responses to hypoxia and other physiological challenges experienced by crustaceans. Published by Elsevier Inc.

Quantification of the oxygen uptake rate in a dissolved oxygen controlled oscillating jet-driven microbioreactor.

PubMed

Kirk, Timothy V; Marques, Marco Pc; Radhakrishnan, Anand N Pallipurath; Szita, Nicolas

2016-03-01

Microbioreactors have emerged as a new tool for early bioprocess development. The technology has advanced rapidly in the last decade and obtaining real-time quantitative data of process variables is nowadays state of the art. In addition, control over process variables has also been achieved. The aim of this study was to build a microbioreactor capable of controlling dissolved oxygen (DO) concentrations and to determine oxygen uptake rate in real time. An oscillating jet driven, membrane-aerated microbioreactor was developed without comprising any moving parts. Mixing times of ∼7 s, and k L a values of ∼170 h -1 were achieved. DO control was achieved by varying the duty cycle of a solenoid microvalve, which changed the gas mixture in the reactor incubator chamber. The microbioreactor supported Saccharomyces cerevisiae growth over 30 h and cell densities of 6.7 g dcw L -1 . Oxygen uptake rates of ∼34 mmol L -1 h -1 were achieved. The results highlight the potential of DO-controlled microbioreactors to obtain real-time information on oxygen uptake rate, and by extension on cellular metabolism for a variety of cell types over a broad range of processing conditions. © 2015 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Oxygen regulates amino acid turnover and carbohydrate uptake during the preimplantation period of mouse embryo development.

PubMed

Wale, Petra L; Gardner, David K

2012-07-01

Oxygen is a powerful regulator of preimplantation embryo development, affecting gene expression, the proteome, and energy metabolism. Even a transient exposure to atmospheric oxygen can have a negative impact on embryo development, which is greatest prior to compaction, and subsequent postcompaction culture at low oxygen cannot alleviate this damage. In spite of this evidence, the majority of human in vitro fertilization is still performed at atmospheric oxygen. One of the physiological parameters shown to be affected by the relative oxygen concentration, carbohydrate metabolism, is linked to the ability of the mammalian embryo to develop in culture and remain viable after transfer. The aim of this study was, therefore, to determine the effect of oxygen concentration on the ability of mouse embryos to utilize both amino acids and carbohydrates both before and after compaction. Metabolomic and fluorometric analysis of embryo culture media revealed that when embryos were exposed to atmospheric oxygen during the cleavage stages, they exhibited significantly greater amino acid utilization and pyruvate uptake than when cultured under 5% oxygen. In contrast, postcompaction embryos cultured in atmospheric oxygen showed significantly lower mean amino acid utilization and glucose uptake. These metabolic changes correlated with developmental compromise because embryos grown in atmospheric oxygen at all stages showed significantly lower blastocyst formation and proliferation. These findings confirm the need to consider both embryo development and metabolism in establishing optimal human embryo growth conditions and prognostic markers of viability, and further highlight the impact of oxygen on such vital parameters.

Relationship between oxygen concentration, respiration and filtration rate in blue mussel Mytilus edulis

NASA Astrophysics Data System (ADS)

Tang, Baojun; Riisgård, Hans Ulrik

2018-03-01

The large water-pumping and particle-capturing gills of the filter-feeding blue mussel Mytilus edulis are oversized for respiratory purposes. Consequently, the oxygen uptake rate of the mussel has been suggested to be rather insensitive to decreasing oxygen concentrations in the ambient water, since the diffusion rate of oxygen from water flowing through the mussel determines oxygen uptake. We tested this hypothesis by measuring the oxygen uptake in mussels exposed to various oxygen concentrations. These concentrations were established via N2-bubbling of the water in a respiration chamber with mussels fed algal cells to stimulate fully opening of the valves. It was found that mussels exposed to oxygen concentrations decreasing from 9 to 2 mg O2/L resulted in a slow but significant reduction in the respiration rate, while the filtration rate remained high and constant. Thus, a decrease of oxygen concentration by 78% only resulted in a 25% decrease in respiration rate. However, at oxygen concentrations below 2 mg O2/L M. edulis responded by gradually closing its valves, resulting in a rapid decrease of filtration rate, concurrent with a rapid reduction of respiration rate. These observations indicated that M. edulis is no longer able to maintain its normal aerobic metabolism at oxygen concentration below 2 mg O2/L, and there seems to be an energy-saving mechanism in bivalve molluscs to strongly reduce their activity when exposed to low oxygen conditions.

Energy requirements of tire pulling.

PubMed

Fredriksen, Per M; Mamen, Asgeir

2017-10-01

We have investigated the effect using walking poles and pulling tires at 4 and 6 km·h-1 (1.11 and 1.67 m·s-1) speeds on oxygen uptake (V̇O2) and heart rate. Eleven subjects, 6 males, with a mean (SD) age of 25.2 (6.9) years participated in field tests involving walking without poles, walking with poles and tire pulling with poles. Increasing the load caused the largest increases in energy demand, more than 4 MET. Speed increase also caused substantial energy increase, approximately 4 MET. Increasing the inclination only modestly increased the oxygen uptake, approximately 2 MET. In both level walking and uphill walking, using poles marginally increased oxygen uptake compared to working without poles. Pulling one tire (12.5 kg) required an oxygen uptake of 27 (4) mL·kg-1·min-1 at 4 km·h-1 and 0% inclination. Adding one more tire (6 kg) drove the oxygen uptake further up to 39 (4) mL·kg-1·min-1. This is close to the requirement of level running at 10.5 km·h-1. Pulling both tires at 6 km·h-1 and 5% inclination required a V̇O2 of 54 (6) mL·kg-1·min-1, equal to running uphill at 5% inclination and 12.5 km·h-1 speed. Heart rate rose comparably with oxygen uptake. At 4 km·h-1 and 0% inclination the increase was 29 bpm, from 134 (21) to 163 (22) bpm when going from pulling one tire to two tires. In the hardest exercise, 6 km·h-1 and 5% inclination, heart rate reached 174 (14) bpm. The study showed that tire pulling even at slow speeds has an energy requirement that is so large that the activity may be feasible as endurance training.

Gymnasium-based unsupervised exercise maintains benefits in oxygen uptake kinetics obtained following supervised training in type 2 diabetes.

PubMed

Macananey, Oscar; O'Shea, Donal; Warmington, Stuart A; Green, Simon; Egaña, Mikel

2012-08-01

Supervised exercise (SE) in patients with type 2 diabetes improves oxygen uptake kinetics at the onset of exercise. Maintenance of these improvements, however, has not been examined when supervision is removed. We explored if potential improvements in oxygen uptake kinetics following a 12-week SE that combined aerobic and resistance training were maintained after a subsequent 12-week unsupervised exercise (UE). The involvement of cardiac output (CO) in these improvements was also tested. Nineteen volunteers with type 2 diabetes were recruited. Oxygen uptake kinetics and CO (inert gas rebreathing) responses to constant-load cycling at 50% ventilatory threshold (V(T)), 80% V(T), and mid-point between V(T) and peak workload (50% Δ) were examined at baseline (on 2 occasions) and following each 12-week training period. Participants decided to exercise at a local gymnasium during the UE. Thirteen subjects completed all the interventions. The time constant of phase 2 of oxygen uptake was significantly faster (p < 0.05) post-SE and post-UE compared with baseline at 50% V(T) (17.3 ± 10.7 s and 17.5 ± 5.9 s vs. 29.9 ± 10.7 s), 80% V(T) (18.9 ± 4.7 and 20.9 ± 8.4 vs. 34.3 ± 12.7s), and 50% Δ (20.4 ± 8.2 s and 20.2 ± 6.0 s vs. 27.6 ± 3.7 s). SE also induced faster heart rate kinetics at all 3 intensities and a larger increase in CO at 30 s in relation to 240 s at 80% V(T); and these responses were maintained post-UE. Unsupervised exercise maintained benefits in oxygen uptake kinetics obtained during a supervised exercise in subjects with diabetes, and these benefits were associated with a faster dynamic response of heart rate after training.

Influence of taekwondo as security martial arts training on anaerobic threshold, cardiorespiratory fitness, and blood lactate recovery.

PubMed

Kim, Dae-Young; Seo, Byoung-Do; Choi, Pan-Am

2014-04-01

[Purpose] This study was conducted to determine the influence of Taekwondo as security martial arts training on anaerobic threshold, cardiorespiratory fitness, and blood lactate recovery. [Subjects and Methods] Fourteen healthy university students were recruited and divided into an exercise group and a control group (n = 7 in each group). The subjects who participated in the experiment were subjected to an exercise loading test in which anaerobic threshold, value of ventilation, oxygen uptake, maximal oxygen uptake, heart rate, and maximal values of ventilation / heart rate were measured during the exercise, immediately after maximum exercise loading, and at 1, 3, 5, 10, and 15 min of recovery. [Results] At the anaerobic threshold time point, the exercise group showed a significantly longer time to reach anaerobic threshold. The exercise group showed significantly higher values for the time to reach VO2max, maximal values of ventilation, maximal oxygen uptake and maximal values of ventilation / heart rate. Significant changes were observed in the value of ventilation volumes at the 1- and 5-min recovery time points within the exercise group; oxygen uptake and maximal oxygen uptake were significantly different at the 5- and 10-min time points; heart rate was significantly different at the 1- and 3-min time points; and maximal values of ventilation / heart rate was significantly different at the 5-min time point. The exercise group showed significant decreases in blood lactate levels at the 15- and 30-min recovery time points. [Conclusion] The study results revealed that Taekwondo as a security martial arts training increases the maximal oxygen uptake and anaerobic threshold and accelerates an individual's recovery to the normal state of cardiorespiratory fitness and blood lactate level. These results are expected to contribute to the execution of more effective security services in emergencies in which violence can occur.

[Effects of carbon sources, temperature and electron acceptors on biological phosphorus removal].

PubMed

Han, Yun; Xu, Song; Dong, Tao; Wang, Bin-Fan; Wang, Xian-Yao; Peng, Dang-Cong

2015-02-01

Effects of carbon sources, temperature and electron acceptors on phosphorus uptake and release were investigated in a pilot-scale oxidation ditch. Phosphorus uptake and release rates were measured with different carbon sources (domestic sewage, sodium acetate, glucose) at 25 degrees C. The results showed that the minimum phosphorus uptake and release rates of glucose were 5.12 mg x (g x h)(-1) and 6.43 mg x (g x h)(-1), respectively, and those of domestic sewage are similar to those of sodium acetate. Phosphorus uptake and release rates increased with the increase of temperature (12, 16, 20 and 25 degrees C) using sodium acetate as carbon sources. Anoxic phosphorus uptake rate decreased with added COD. Electron acceptors (oxygen, nitrate, nitrite) had significant effects on phosphorus uptake rate and their order was in accordance with oxygen > nitrate > nitrite. The mass ratio of anoxic P uptake and N consumption (P(uptake)/N (consumption)) of nitrate and nitrite were 0.96 and 0.65, respectively.

The influence of different space-related physiological variations on exercise capacity determined by oxygen uptake kinetics.

PubMed

Stegemann, J

1992-07-01

Oxygen uptake kinetics, following defined variations of work load changes allow to estimate the contribution of aerob and anaerob energy supply which is the base for determining work capacity. Under the aspect of long duration missions with application of adequate dosed countermeasures, a reliable estimate of the astronaut's work capacity is important to adjust the necessary inflight training. Since the kinetics of oxygen uptake originate in the working muscle group itself, while measurements are performed at the mouth, various influences within the oxygen transport system might disturb the determinations. There are not only detraining effects but also well-known other influences, such as blood- and fluid shifts induced by weightlessness. They might have an impact on the circulatory system. Some of these factors have been simulated by immersion, blood donation, and changing of the body position.

The influence of different space-related physiological variations on exercise capacity determined by oxygen uptake kinetics

NASA Astrophysics Data System (ADS)

Stegemann, J.

Oxygen uptake kinetics, following defined variations of work load changes allow to estimate the contribution of aerob and anaerob energy supply which is the base for determining work capacity. Under the aspect of long duration missions with application of adequate dosed countermeasures, a reliable estimate of the astronaut's work capacity is important to adjust the necessary inflight training. Since the kinetics of oxygen uptake originate in the working muscle group itself, while measurements are performed at the mouth, various influences within the oxygen transport system might disturb the determinations. There are not only detraining effects but also well-known other influences, such as blood- and fluid shifts induced by weightlessness. They might have an impact on the circulatory system. Some of these factors have been simulated by immersion, blood donation, and changing of the body position.

Glossosoma nigrior (Trichoptera: Glossosomatidae) respiration in moving fluid.

PubMed

Morris, Mark W L; Hondzo, Miki

2013-08-15

Laboratory measurements of dissolved oxygen (DO) uptake by Glossosoma nigrior Banks were conducted in a sealed, recirculating flume under variable fluid flow velocities. Measurements were performed in similar water temperatures, DO concentrations and fluid flow velocities to field conditions in the stream where the larvae were obtained. Total oxygen uptake by both cased larvae and corresponding cases without larvae were quantified. An increased fluid flow velocity corresponded to an increased larval DO uptake rate. Oxygen uptake by the larval cases alone was not as sensitive to changes in the Peclet (Pe) number, the dimensionless ratio of advective to diffusive DO transport, as uptake by larvae themselves. The flux of DO to larvae and their cases was up to seven times larger in a moving fluid in comparison to non-moving fluid conditions in the proximity of larvae for 087, larvae typically remained in their cases. This indicates that oxygen delivery to the larvae at low Pe is insufficient to satisfy the respiratory demands of cased larvae.

Reverse Engineering of Oxygen Transport in the Lung: Adaptation to Changing Demands and Resources through Space-Filling Networks

PubMed Central

Hou, Chen; Gheorghiu, Stefan; Huxley, Virginia H.; Pfeifer, Peter

2010-01-01

The space-filling fractal network in the human lung creates a remarkable distribution system for gas exchange. Landmark studies have illuminated how the fractal network guarantees minimum energy dissipation, slows air down with minimum hardware, maximizes the gas- exchange surface area, and creates respiratory flexibility between rest and exercise. In this paper, we investigate how the fractal architecture affects oxygen transport and exchange under varying physiological conditions, with respect to performance metrics not previously studied. We present a renormalization treatment of the diffusion-reaction equation which describes how oxygen concentrations drop in the airways as oxygen crosses the alveolar membrane system. The treatment predicts oxygen currents across the lung at different levels of exercise which agree with measured values within a few percent. The results exhibit wide-ranging adaptation to changing process parameters, including maximum oxygen uptake rate at minimum alveolar membrane permeability, the ability to rapidly switch from a low oxygen uptake rate at rest to high rates at exercise, and the ability to maintain a constant oxygen uptake rate in the event of a change in permeability or surface area. We show that alternative, less than space-filling architectures perform sub-optimally and that optimal performance of the space-filling architecture results from a competition between underexploration and overexploration of the surface by oxygen molecules. PMID:20865052

Contribution of aerial hyphae of Aspergillus oryzae to respiration in a model solid-state fermentation system.

PubMed

Rahardjo, Yovita S P; Weber, Frans J; le Comte, E Paul; Tramper, Johannes; Rinzema, Arjen

2002-06-05

Oxygen transfer is for two reasons a major concern in scale-up and process control in industrial application of aerobic fungal solid-state fermentation (SSF): 1) heat production is proportional to oxygen uptake and it is well known that heat removal is one of the main problems in scaled-up fermenters, and 2) oxygen supply to the mycelium on the surface of or inside the substrate particles may be hampered by diffusion limitation. This article gives the first experimental evidence that aerial hyphae are important for fungal respiration in SSF. In cultures of A. oryzae on a wheat-flour model substrate, aerial hyphae contributed up to 75% of the oxygen uptake rate by the fungus. This is due to the fact that A. oryzae forms very abundant aerial mycelium and diffusion of oxygen in the gas-filled pores of the aerial hyphae layer is rapid. It means that diffusion limitation in the densely packed mycelium layer that is formed closer to the substrate surface and that has liquid-filled pores is much less important for A. oryzae than was previously reported for R. oligosporus and C. minitans. It also means that the overall oxygen uptake rate for A. oryzae is much higher than the oxygen uptake rate that can be predicted in the densely packed mycelium layer for R. oligosporus and C. minitans. This would imply that cooling problems become more pronounced. Therefore, it is very important to clarify the physiological role of aerial hyphae in SSF. Copyright 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 78: 539-544, 2002.

Assessment by near-infrared spectroscopy of the consumption of oxygen provoked by the human body weight in the vastus medialis muscle

NASA Astrophysics Data System (ADS)

Verdaguer-Codina, Joan

1996-12-01

This study has been focused to find the importance of the consumption of oxygen for a muscle that works supporting the weight of the human body. The oxygen uptake at rest level is a data know, but by near-IR spectroscopy can be assessed the oxygen uptake used for a muscle. The energy required by the human body is partially used to produce the energy that help to move the human structure. The oxygen required by the muscles to produce the energy to support the human body has been defined as weight oxygen consumption. The purpose of this study was to assess by near-IR spectroscopy the amount of relative oxygenation/deoxygenation that a muscle requires at rest level and a middle-term rest level.

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

PubMed

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

2016-05-01

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

Direct measurements of the light dependence of gross photosynthesis and oxygen consumption in the ocean

NASA Astrophysics Data System (ADS)

Bailleul, B.; Park, J.; Brown, C. M.; Bidle, K. D.; Lee, S.; Falkowski, P. G.

2016-02-01

For decades, a lack of understanding of how respiration is influenced by light has been stymying our ability to quantitatively analyze how phytoplankton allocate carbon in situ and the biological mechanisms that participate to the fate of blooms. Using membrane inlet mass spectrometry (MIMS), the light dependencies of gross photosynthesis and oxygen uptake rates were measured during the bloom demises of two prymnesiophytes, in two open ocean regions. In the North Atlantic, dominated by Emiliania huxleyi, respiration was independent of irradiance and was higher than the gross photosynthetic rate at all irradiances. In the Amundsen Sea (Antarctica), dominated by Phaeocystis antarctica, the situation was very different. Dark respiration was one order of magnitude lower than the maximal gross photosynthetic rate. ut the oxygen uptake rate increased by 10 fold at surface irradiances, where it becomes higher than gross photosynthesis. Our results suggest that the light dependence of oxygen uptake in P. antarctica has two sources: one is independent of photosynthesis, and is possibly associated with the photo-reduction of O2 mediated by dissolved organic matter; the second reflects the activity of an oxidase fueled in the light with photosynthetic electron flow. Interestingly, these dramatic light-dependent changes in oxygen uptake were not reproduced in nutrient-replete P. antarctica cultures, in the laboratory. Our measurements highlight the importance of improving our understanding of oxygen consuming reactions in the euphotic zone, which is critical to investigating the physiology of phytoplankton and tracing the fate of phytoplankton blooms.

Effects of combined high intensity arm and leg training on performance and cardio-respiratory measures.

PubMed

Zinner, Christoph; Sperlich, Billy; Born, Dennis-Peter; Michels, Guido

2017-01-01

The purpose of this study was to investigate the effects of combined arm and leg high-intensity low-volume interval training (HIITarm+leg) on maximal oxygen uptake, myocardial measures (i.e. stroke volume, cardiac output, ejection fraction), Tissue Oxygenation Index (TOI) of the vastus lateralis and triceps brachii, as well as power output in comparison to leg HIIT (HIITleg) only. The 20 healthy, male and female volunteers completed six sessions of either HIITleg on a cycle ergometer or HIITarm+leg on an arm and leg cycle ergometer. During pre- and post-testing, the volunteers completed a submaximal and incremental test to exhaustion on a cycle ergometer. Magnitude based interference revealed likely to very likely beneficial effects for HIITarm+leg compared to HIITleg in maximal oxygen uptake, cardiac measures as well peak power output. The TOI following HIITarm+leg demonstrated likely to very likely increased oxygenation in the triceps brachii or the vastus lateralis when compared to HIITleg. The results suggest that six sessions of HIITarm+leg may likely to very likely improve maximal oxygen uptake, some inotropy-related cardiac measures with improved tissue oxygenation of the triceps brachii and vastus lateralis muscles resulting in greater leg peak power output.

Modeling and analysis of the effect of training on V O2 kinetics and anaerobic capacity.

PubMed

Stirling, J R; Zakynthinaki, M S; Billat, V

2008-07-01

In this paper, we present an application of a number of tools and concepts for modeling and analyzing raw, unaveraged, and unedited breath-by-breath oxygen uptake data. A method for calculating anaerobic capacity is used together with a model, in the form of a set of coupled nonlinear ordinary differential equations to make predictions of the VO(2) kinetics, the time to achieve a percentage of a certain constant oxygen demand, and the time limit to exhaustion at intensities other than those in which we have data. Speeded oxygen kinetics and increased time limit to exhaustion are also investigated using the eigenvalues of the fixed points of our model. We also use a way of analyzing the oxygen uptake kinetics using a plot of V O(2)(t) vs V O(2)(t) which allows one to observe both the fixed point solutions and also the presence of speeded oxygen kinetics following training. A method of plotting the eigenvalue versus oxygen demand is also used which allows one to observe where the maximum amplitude of the so-called slow component will be and also how training has changed the oxygen uptake kinetics by changing the strength of the attracting fixed point for a particular demand.

A strategy to determine operating parameters in tissue engineering hollow fiber bioreactors

PubMed Central

Shipley, RJ; Davidson, AJ; Chan, K; Chaudhuri, JB; Waters, SL; Ellis, MJ

2011-01-01

The development of tissue engineering hollow fiber bioreactors (HFB) requires the optimal design of the geometry and operation parameters of the system. This article provides a strategy for specifying operating conditions for the system based on mathematical models of oxygen delivery to the cell population. Analytical and numerical solutions of these models are developed based on Michaelis–Menten kinetics. Depending on the minimum oxygen concentration required to culture a functional cell population, together with the oxygen uptake kinetics, the strategy dictates the model needed to describe mass transport so that the operating conditions can be defined. If cmin ≫ Km we capture oxygen uptake using zero-order kinetics and proceed analytically. This enables operating equations to be developed that allow the user to choose the medium flow rate, lumen length, and ECS depth to provide a prescribed value of cmin. When , we use numerical techniques to solve full Michaelis–Menten kinetics and present operating data for the bioreactor. The strategy presented utilizes both analytical and numerical approaches and can be applied to any cell type with known oxygen transport properties and uptake kinetics. PMID:21370228

Rapid adaptation of activated sludge bacteria into a glycogen accumulating biofilm enabling anaerobic BOD uptake.

PubMed

Hossain, Md Iqbal; Paparini, Andrea; Cord-Ruwisch, Ralf

2017-03-01

Glycogen accumulating organisms (GAO) are known to allow anaerobic uptake of biological oxygen demand (BOD) in activated sludge wastewater treatment systems. In this study, we report a rapid transition of suspended activated sludge biomass to a GAO dominated biofilm by selective enrichment using sequences of anaerobic loading followed by aerobic exposure of the biofilm to air. The study showed that within eight weeks, a fully operational, GAO dominated biofilm had developed, enabling complete anaerobic BOD uptake at a rate of 256mg/L/h. The oxygen uptake by the biofilm directly from the atmosphere had been calculated to provide significant energy savings. This study suggests that wastewater treatment plant operators can convert activated sludge systems readily into a "passive aeration" biofilm that avoids costly oxygen transfer to bulk wastewater solution. The described energy efficient BOD removal system provides an opportunity to be coupled with novel nitrogen removal processes such as anammox. Copyright © 2016. Published by Elsevier Ltd.

Body acceleration distribution and O2 uptake in humans during running and jumping

NASA Technical Reports Server (NTRS)

Bhattacharya, A.; Mccutcheon, E. P.; Shvartz, E.; Greenleaf, J. E.

1980-01-01

The distribution of body acceleration and associated oxygen uptake and heart rate responses are investigated in treadmill running and trampoline jumping. Accelerations in the +Gz direction were measured at the lateral ankle, lumbosacral region and forehead of eight young men during level treadmill walking and running at four speeds and trampoline jumping at four heights, together with corresponding oxygen uptake and heart rate. With increasing treadmill speed, peak acceleration at the ankle is found always to exceed that at the back and forehead, and acceleration profiles with higher frequency components than those observed during jumping are observed. Acceleration levels are found to be more uniformly distributed with increasing height in jumping, although comparable oxygen uptake and heat rates are obtained. Results indicate that the magnitude of the biomechanical stimuli is greater in trampoline jumping than in running, which finding could be of use in the design of procedures to avert deconditioning in persons exposed to weightlessness.

Hydrologic and geochemical effects on oxygen uptake in bottom sediments of an effluent-dominated river

USGS Publications Warehouse

McMahon, P.B.; Tindall, J.A.; Collins, J.A.; Lull, K.J.; Nuttle, J.R.

1995-01-01

More than 95% of the water in the South Platte River downstream from the largest wastewater treatment plant serving the metropolitan Denver, Colorado, area consists of treated effluent during some periods of low flow. Fluctuations in effluent-discharge rates caused daily changes in river stage that promoted exchange of water between the river and bottom sediments. Groundwater discharge measurements indicated fluxes of water across the sediment-water interface as high as 18 m3 s−1 km−1. Laboratory experiments indicated that downward movement of surface water through bottom sediments at velocities comparable to those measured in the field (median rate ≈0.005 cm s−1) substantially increased dissolved oxygen uptake rates in bottom sediments (maximum rate 212 ± 10 μmol O2 L−1 h−1) compared with rates obtained when no vertical advective flux was generated (maximum rate 25 ± 8.8 μmol O2 L−1 h−1). Additions of dissolved ammonium to surface waters generally increased dissolved oxygen uptake rates relative to rates measured in experiments without ammonium. However, the magnitude of the advective flux through bottom sediments had a greater effect on dissolved oxygen uptake rates than did the availability of ammonium. Results from this study indicated that efforts to improve dissolved oxygen dynamics in effluent-dominated rivers might include stabilizing daily fluctuations in river stage.

Preserved arterial flow secures hepatic oxygenation during haemorrhage in the pig

PubMed Central

Rasmussen, Allan; Skak, Claus; Kristensen, Michael; Ott, Peter; Kirkegaard, Preben; Secher, Niels H

1999-01-01

This study examined the extent of liver perfusion and its oxygenation during progressive haemorrhage. We examined hepatic arterial flow and hepatic oxygenation following the reduced portal flow during haemorrhage in 18 pigs. The hepatic surface oxygenation was assessed by near-infrared spectroscopy and the hepatic metabolism of oxygen, lactate and catecholamines determined the adequacy of the hepatic flow. Stepwise haemorrhage until circulatory collapse resulted in proportional reductions in cardiac output and in arterial, central venous and pulmonary wedge pressures. While heart rate increased, pulmonary arterial pressure remained stable. In addition, renal blood flow decreased, renal vascular resistance increased and there was elevated noradrenaline spill-over. Further, renal surface oxygenation was lowered from the onset of haemorrhage. Similarly, the portal blood flow was reduced in response to haemorrhage, and, as for the renal flow, the reduced splanchnic blood flow was associated with an elevated noradrenaline spill-over. In contrast, hepatic arterial blood flow was only slightly reduced by haemorrhage, and surface oxygenation did not change. The hepatic oxygen uptake was maintained until the blood loss represented more than 30 % of the estimated blood volume. At 30 % reduced blood volume, hepatic catecholamine uptake was reduced, and the lactate uptake approached zero. Subsequent reduction of cardiac output and portal blood flow elicited a selective dilatation of the hepatic arterial vascular bed. Due to this dilatation liver blood flow and hepatic cell oxygenation and metabolism were preserved prior to circulatory collapse. PMID:10087351

Reversible uptake of molecular oxygen by heteroligand Co(II)-L-α-amino acid-imidazole systems: equilibrium models at full mass balance.

PubMed

Pająk, Marek; Woźniczka, Magdalena; Vogt, Andrzej; Kufelnicki, Aleksander

2017-09-19

The paper examines Co(II)-amino acid-imidazole systems (where amino acid = L-α-amino acid: alanine, asparagine, histidine) which, when in aqueous solutions, activate and reversibly take up dioxygen, while maintaining the structural scheme of the heme group (imidazole as axial ligand and O 2 uptake at the sixth, trans position) thus imitating natural respiratory pigments such as myoglobin and hemoglobin. The oxygenated reaction shows higher reversibility than for Co(II)-amac systems with analogous amino acids without imidazole. Unlike previous investigations of the heteroligand Co(II)-amino acid-imidazole systems, the present study accurately calculates all equilibrium forms present in solution and determines the [Formula: see text]equilibrium constants without using any simplified approximations. The equilibrium concentrations of Co(II), amino acid, imidazole and the formed complex species were calculated using constant data obtained for analogous systems under oxygen-free conditions. Pehametric and volumetric (oxygenation) studies allowed the stoichiometry of O 2 uptake reaction and coordination mode of the central ion in the forming oxygen adduct to be determined. The values of dioxygen uptake equilibrium constants [Formula: see text] were evaluated by applying the full mass balance equations. Investigations of oxygenation of the Co(II)-amino acid-imidazole systems indicated that dioxygen uptake proceeds along with a rise in pH to 9-10. The percentage of reversibility noted after acidification of the solution to the initial pH ranged within ca 30-60% for alanine, 40-70% for asparagine and 50-90% for histidine, with a rising tendency along with the increasing share of amino acid in the Co(II): amino acid: imidazole ratio. Calculations of the share of the free Co(II) ion as well as of the particular complex species existing in solution beside the oxygen adduct (regarding dioxygen bound both reversibly and irreversibly) indicated quite significant values for the systems with alanine and asparagine-in those cases the of oxygenation reaction is right shifted to a relatively lower extent. The experimental results indicate that the "active" complex, able to take up dioxygen, is a heteroligand CoL 2 L'complex, where L = amac (an amino acid with a non-protonated amine group) while L' = Himid, with the N1 nitrogen protonated within the entire pH range under study. Moreover, the corresponding log  [Formula: see text] value at various initial total Co(II), amino acid and imidazole concentrations was found to be constant within the limits of error, which confirms those results. The highest log [Formula: see text] value, 14.9, occurs for the histidine system; in comparison, asparagine is 7.8 and alanine is 9.7. This high value is most likely due to the participation of the additional effective N3 donor of the imidazole side group of histidine. The Co(II)-amac-Himid systems formed by using a [Co(imid) 2 ] n polymer as starting material demonstrate that the reversible uptake of molecular oxygen occurs by forming dimeric μ-peroxy adducts. The essential impact on the electron structure of the dioxygen bridge, and therefore, on the reversibility of O 2 uptake, is due to the imidazole group at axial position (trans towards O 2 ). However, the results of reversibility measurements of O 2 uptake, unequivocally indicate a much higher effectiveness of dioxygenation than in systems in which the oxygen adducts are formed in equilibrium mixtures during titration of solutions containing Co(II) ions, the amino acid and imidazole, separately.

Central Cardiovascular Responses of Quadriplegic Subjects to Arm Exercise at Varying Levels of Oxygen Uptake.

ERIC Educational Resources Information Center

Figoni, Stephen F.

The purpose of this study was to assess selected central cardiovascular functions of spinal cord injured, quadriplegic subjects at varying levels of oxygen uptake (VO sub 2). Subjects included 11 untrained, male college students with C5, C6, or C7 complete quadriplegia and 11 able-bodied reference subjects. Exercise was performed on a Monark cycle…

Fitting a single-phase model to the post-exercise changes in heart rate and oxygen uptake.

PubMed

Stupnicki, R; Gabryś, T; Szmatlan-Gabryś, U; Tomaszewski, P

2010-01-01

The kinetics of post-exercise heart rate (HR) and oxygen consumption (EPOC) was studied in 10 elite cyclists subjected to four laboratory cycle ergometer maximal exercises lasting 30, 90, 180 or 360 s. Heart rate and oxygen uptake (VO2) were recorded over a period of 6 min after the exercise. By applying the logit transformation to the recorded variables and relating them to the decimal logarithm of the recovery time, uniform single-phase courses of changes were shown for both variables in all subjects and exercises. This enabled computing half-recovery times (t(1/2)) for both variables. Half-time for VO2 negatively correlated with square root of exercise duration (within-subject r = -0.629, p < 0.001), the total post-exercise oxygen uptake till t(1/2) was thus constant irrespectively of exercise intensity. The method is simple and enables reliable comparisons of various modes of exercise with respect to the rate of recovery.

Oxygen uptake and local Po2 profiles in submerged larvae of phaeoxantha klugii (Coleoptera: Cicindelidae), as well as their metabolic rate in air.

PubMed

Zerm, M; Zinkler, D; Adis, J

2004-01-01

We studied whether oxygen uptake from the surrounding water might enhance survival in submerged third instar larvae of Phaeoxantha klugii, a tiger beetle from the central Amazonian floodplains. Local oxygen partial pressures (Po(2)) were measured with microcoaxial needle electrodes close to larvae submerged in initially air-saturated still water. The Po(2) profiles showed that the larvae exploit oxygen from the aquatic medium. Metabolism in the air of more or less resting larvae was determined by measuring the rate of CO(2) production (sV dot co2) with an infrared gas analyzer at 29 degrees C. The sV dot co2 was around 1.8 mu L g(-1) min(-1), equivalent to an oxygen consumption rate (sV dot o2) of 1.8-2.6 mu L g(-1) min(-1). Oxygen consumption (V dot o2) of individually submerged larvae measured in closed respiration chambers at 19-10.3 kPa Po(2) (initially air saturated, 29 degrees C) ranged between 0.05 and 0.2 mu L min(-1) and was not correlated with body mass. The sV dot o2 ranged between 0.1 and 0.4 mu L min(-1), that is, 4%-22% of the metabolic rate measured in air. Mean V dot o2 decreased with declining Po(2); however, some individuals showed contrary patterns. V dot o2 was additionally measured in dormant larvae, in larvae submerged for 1-2 d in open water or for 30-49 d within sediment, as well as in larvae exposed to anoxia before the measurements. The range of V dot o2 was similar in all groups, indicating that the larvae exploit oxygen from the water whenever available. Similar V dot o2 across the whole range of body mass investigated (0.31-0.76 g) suggests that oxygen uptake occurs by spiracular uptake. Assuming that larvae survive for some time at rates comparable to depressed metabolic rates reported for other insect species, it can be concluded that oxygen uptake from water can sustain aerobic metabolism even under quite severe hypoxia. It might therefore play an important role for survival during inundation periods.

The influence of exercise duration at VO2 max on the off-transient pulmonary oxygen uptake phase during high intensity running activity.

PubMed

Billat, V L; Hamard, L; Koralsztein, J P

2002-12-01

The purpose of this study was to examine the influence of time run at maximal oxygen uptake (VO2 max) on the off-transient pulmonary oxygen uptake phase after supra-lactate threshold runs. We hypothesised: 1) that among the velocities eliciting VO2 max there is a velocity threshold from which there is a slow component in the VO2-off transient, and 2) that at this velocity the longer the duration of this time at VO2 max (associated with an accumulated oxygen kinetics since VO2 can not overlap VO2 max), the longer is the off-transient phase of oxygen uptake kinetics. Nine long-distance runners performed five maximal tests on a synthetic track (400 m) while breathing through the COSMED K4b2 portable, telemetric metabolic analyser: i) an incremental test which determined VO2 max, the minimal velocity associated with VO2 max (vVO2 max) and the velocity at the lactate threshold (vLT), ii) and in a random order, four supra-lactate threshold runs performed until exhaustion at vLT + 25, 50, 75 and 100% of the difference between vLT and vVO2 max (vdelta25, vdelta50, vdelta75, vdelta100). At vdelta25, vdelta50 (= 91.0 +/- 0.9% vVO2 max) and vdelta75, an asymmetry was found between the VO2 on (double exponential) and off-transient (mono exponential) phases. Only at vdelta75 there was at positive relationship between the time run at VO2 max (%tlimtot) and the VO2 recovery time constant (Z = 1.8, P = 0.05). In conclusion, this study showed that among the velocities eliciting VO2 max, vdelta75 is the velocity at which the longer the duration of the time at VO2 max, the longer is the off-transient phase of oxygen uptake kinetics. It may be possible that at vdelta50 there is not an accumulated oxygen deficit during the plateau of VO2 at VO2 max and that the duration of the time at VO2 max during the exhaustive runs at vdelta100, could be too short to induce an accumulating oxygen deficit affecting the oxygen recovery.

Maximal and submaximal oxygen uptakes and blood lactate levels in elite male middle- and long-distance runners.

PubMed

Svedenhag, J; Sjödin, B

1984-10-01

Physiological characteristics of elite runners from different racing events were studied. Twenty-seven middle- and long-distance runners and two 400-m runners belonging to the Swedish national team in track and field were divided, according to their distance preferences, into six groups from 400 m up to the marathon. The maximal oxygen uptake (VO2 max, ml X kg-1 X min-1) on the treadmill was higher the longer the main distance except for the marathon runners (e.g., 800-1500-m group, 72.1; 5000-10,000-m group, 78.7 ml X kg-1 X min-1). Running economy evaluated from oxygen uptake measurements at 15 km/h (VO2 15) and 20 km/h (VO2 20) did not differ significantly between the groups even though VO2 15 tended to be lower in the long-distance runners. The running velocity corresponding to a blood lactate concentration of 4 mmol/l (vHla 4.0) differed markedly between the groups with the highest value (5.61 m/s) in the 5000-10,000-m group. The oxygen uptake (VO2) at vHla 4.0 in percentage of VO2 max did not differ significantly between the groups. The blood lactate concentration after exhaustion (VO2 max test) was lower in the long-distance runners. In summary, the present study demonstrates differences in physiological characteristics of elite runners specializing in different racing events. The two single (but certainly inter-related) variables in which this was most clearly seen were the maximal oxygen uptake (ml X kg-1 X min-1) and the running velocity corresponding to a blood lactate concentration of 4 mmol/l.

Faster heart rate and muscular oxygen uptake kinetics in type 2 diabetes patients following endurance training.

PubMed

Koschate, Jessica; Drescher, Uwe; Brinkmann, Christian; Baum, Klaus; Schiffer, Thorsten; Latsch, Joachim; Brixius, Klara; Hoffmann, Uwe

2016-11-01

Cardiorespiratory kinetics were analyzed in type 2 diabetes patients before and after a 12-week endurance exercise-training intervention. It was hypothesized that muscular oxygen uptake and heart rate (HR) kinetics would be faster after the training intervention and that this would be detectable using a standardized work rate protocol with pseudo-random binary sequences. The cardiorespiratory kinetics of 13 male sedentary, middle-aged, overweight type 2 diabetes patients (age, 60 ± 8 years; body mass index, 33 ± 4 kg·m -2 ) were tested before and after the 12-week exercise intervention. Subjects performed endurance training 3 times a week on nonconsecutive days. Pseudo-random binary sequences exercise protocols in combination with time series analysis were used to estimate kinetics. Greater maxima in cross-correlation functions (CCF max ) represent faster kinetics of the respective parameter. CCF max of muscular oxygen uptake (pre-training: 0.31 ± 0.03; post-training: 0.37 ± 0.1, P = 0.024) and CCF max of HR (pre-training: 0.25 ± 0.04; post-training: 0.29 ± 0.06, P = 0.007) as well as peak oxygen uptake (pre-training: 24.4 ± 4.7 mL·kg -1 ·min -1 ; post-training: 29.3 ± 6.5 mL·kg -1 ·min -1 , P = 0.004) increased significantly over the course of the exercise intervention. In conclusion, kinetic responses to changing work rates in the moderate-intensity range are similar to metabolic demands occurring in everyday habitual activities. Moderate endurance training accelerated the kinetic responses of HR and muscular oxygen uptake. Furthermore, the applicability of the used method to detect these accelerations was demonstrated.

Dispersible oxygen microsensors map oxygen gradients in three-dimensional cell cultures.

PubMed

Lesher-Pérez, Sasha Cai; Kim, Ge-Ah; Kuo, Chuan-Hsien; Leung, Brendan M; Mong, Sanda; Kojima, Taisuke; Moraes, Christopher; Thouless, M D; Luker, Gary D; Takayama, Shuichi

2017-09-26

Phase fluorimetry, unlike the more commonly used intensity-based measurement, is not affected by differences in light paths from culture vessels or by optical attenuation through dense 3D cell cultures and hydrogels thereby minimizing dependence on signal intensity for accurate measurements. This work describes the use of phase fluorimetry on oxygen-sensor microbeads to perform oxygen measurements in different microtissue culture environments. In one example, cell spheroids were observed to deplete oxygen from the cell-culture medium filling the bottom of conventional microwells within minutes, whereas oxygen concentrations remained close to ambient levels for several days in hanging-drop cultures. By dispersing multiple oxygen microsensors in cell-laden hydrogels, we also mapped cell-generated oxygen gradients. The spatial oxygen mapping was sufficiently precise to enable the use of computational models of oxygen diffusion and uptake to give estimates of the cellular oxygen uptake rate and the half-saturation constant. The results show the importance of integrated design and analysis of 3D cell cultures from both biomaterial and oxygen supply aspects. While this paper specifically tests spheroids and cell-laden gel cultures, the described methods should be useful for measuring pericellular oxygen concentrations in a variety of biomaterials and culture formats.

Role of hemoglobin and capillarization for oxygen delivery and extraction in muscular exercise.

PubMed

Saltin, B; Kiens, B; Savard, G; Pedersen, P K

1986-01-01

Through the years the role of the various links in the transport of oxygen in the human body has been discussed extensively, and especially whether one of these links could be singled out as limiting oxygen uptake during exercise. In his thesis work Lars Hermansen dealt with several of these variables related to oxygen transport and uptake. Two of these were the hemoglobin concentration of the blood (Hb) and skeletal muscle capillarization. These are the focus of this article. It can be demonstrated that variation in arterial oxygen content due to different Hb concentrations is fully compensated for at the level of the muscle, i.e. the amount of oxygen delivered to contracting muscles is adjusted by a variation in the blood flow so that it is the same regardless of Hb concentration in the range of 118-172 g X l-1. At the systemic level, with a large fraction of the muscle exercising, this causes an increase in submaximal heart rate and a lowering in maximal oxygen uptake in people with low as compared to normal or high Hb concentration. The primary significance of an enlarged capillary network in the muscle does not appear to be for accommodating a larger flow, but rather to allow for a long enough mean transit time and large enough surface area for optimal exchange of gases, substrates and metabolites.

Impact of oxygen status on 10B-BPA uptake into human glioblastoma cells, referring to significance in boron neutron capture therapy

PubMed Central

Wada, Yuki; Hirose, Katsumi; Harada, Takaomi; Sato, Mariko; Watanabe, Tsubasa; Anbai, Akira; Hashimoto, Manabu; Takai, Yoshihiro

2018-01-01

Abstract Boron neutron capture therapy (BNCT) can potentially deliver high linear energy transfer particles to tumor cells without causing severe damage to surrounding normal tissue, and may thus be beneficial for cases with characteristics of infiltrative growth, which need a wider irradiation field, such as glioblastoma multiforme. Hypoxia is an important factor contributing to resistance to anticancer therapies such as radiotherapy and chemotherapy. In this study, we investigated the impact of oxygen status on 10B uptake in glioblastoma cells in vitro in order to evaluate the potential impact of local hypoxia on BNCT. T98G and A172 glioblastoma cells were used in the present study, and we examined the influence of oxygen concentration on cell viability, mRNA expression of L-amino acid transporter 1 (LAT1), and the uptake amount of 10B-BPA. T98G and A172 glioblastoma cells became quiescent after 72 h under 1% hypoxia but remained viable. Uptake of 10B-BPA, which is one of the agents for BNCT in clinical use, decreased linearly as oxygen levels were reduced from 20% through to 10%, 3% and 1%. Hypoxia with <10% O2 significantly decreased mRNA expression of LAT1 in both cell lines, indicating that reduced uptake of 10B-BPA in glioblastoma in hypoxic conditions may be due to reduced expression of this important transporter protein. Hypoxia inhibits 10B-BPA uptake in glioblastoma cells in a linear fashion, meaning that approaches to overcoming local tumor hypoxia may be an effective method of improving the success of BNCT treatment. PMID:29315429

Oxygen- and Lithium-Doped Hybrid Boron-Nitride/Carbon Networks for Hydrogen Storage.

PubMed

Shayeganfar, Farzaneh; Shahsavari, Rouzbeh

2016-12-20

Hydrogen storage capacities have been studied on newly designed three-dimensional pillared boron nitride (PBN) and pillared graphene boron nitride (PGBN). We propose these novel materials based on the covalent connection of BNNTs and graphene sheets, which enhance the surface and free volume for storage within the nanomaterial and increase the gravimetric and volumetric hydrogen uptake capacities. Density functional theory and molecular dynamics simulations show that these lithium- and oxygen-doped pillared structures have improved gravimetric and volumetric hydrogen capacities at room temperature, with values on the order of 9.1-11.6 wt % and 40-60 g/L. Our findings demonstrate that the gravimetric uptake of oxygen- and lithium-doped PBN and PGBN has significantly enhanced the hydrogen sorption and desorption. Calculations for O-doped PGBN yield gravimetric hydrogen uptake capacities greater than 11.6 wt % at room temperature. This increased value is attributed to the pillared morphology, which improves the mechanical properties and increases porosity, as well as the high binding energy between oxygen and GBN. Our results suggest that hybrid carbon/BNNT nanostructures are an excellent candidate for hydrogen storage, owing to the combination of the electron mobility of graphene and the polarized nature of BN at heterojunctions, which enhances the uptake capacity, providing ample opportunities to further tune this hybrid material for efficient hydrogen storage.

Influence of aquatic training on the motor performance of patients with haemophilic arthropathy.

PubMed

Vallejo, L; Pardo, A; Gomis, M; Gallach, J E; Pérez, S; Querol, F

2010-01-01

Thirteen patients with haemophilia A took part in this study voluntarily. They underwent an aquatic training programme over a 9-week period (27 sessions; three sessions per week; 1 h per session). Their motor performance was assessed by the following cardio-respiratory and mechanical variables before and after the training programme: oxygen uptake (VO(2), mL min(-1)), relative oxygen uptake (rel VO(2), mL min(-1).kg(-1)), carbon dioxide (CO(2), mL min(-1)), respiratory quotient (R), heart rate (bpm) and the distance covered in 12 min (the Cooper test, m). Nine patients successfully completed the intervention and measurement protocols without bleeding or other adverse events. After the proposed training programme, significant differences between the pre-test and post-test were observed. Patients' aerobic capacity increased considerably, and their oxygen uptake improved by 51.51% (P < 0.05), while their relative oxygen uptake went up by 37.73% (P < 0.05). Their mechanical capacity also increased considerably (14.68%, P < 0.01). Our results suggest that 27 specially designed aquatic training sessions for our patients with haemophilia A had a positive effect on their motor performance and considerably improved their aerobic and mechanical capacity without causing adverse effects.

Protein synthesis and specific dynamic action in crustaceans: effects of temperature.

PubMed

Whiteley, N M; Robertson, R F; Meagor, J; El Haj, A J; Taylor, E W

2001-03-01

Temperature influences the specific dynamic action (SDA), or rise in oxygen uptake rate after feeding, in eurythermal and stenothermal crustaceans by changing the timing and the magnitude of the response. Intra-specific studies on the eurythermal crab, Carcinus maenas, show that a reduction in acclimation temperature is associated with a decrease in SDA magnitude, resulting from an increase in SDA duration but a decrease in peak factorial scope (the factorial rise in peak SDA over prefeeding values). Inter-specific feeding studies on stenothermal polar isopods revealed marked differences in SDA response between the Antarctic species, Glyptonotus antarcticus and the Arctic species, Saduria entomon. Compared to S. entomon held at 4 and 13 degrees C, the SDA response in G. antarcticus held at 1 degrees C was characterised by a lower absolute oxygen uptake rate at peak SDA and an extended SDA duration. At peak SDA, whole animal rates of protein synthesis increased in proportion to the postprandial increase in oxygen uptake rate in the Antarctic and the Arctic species. Rates of oxygen uptake plotted against whole animal rates of protein synthesis gave similar relationships in both isopod species, indicating similar costs of protein synthesis after a meal, despite their differences in SDA response and thermal habitat.

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

PubMed

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

2015-12-15

Type 2 diabetes mellitus (DM) is responsible for a significant reduction in the quality of life due to its negative impact on functional capacity. Cardiopulmonary fitness impairment in DM patients has been associated with limited tissue oxygenation. Phototherapy is widely utilized to treat several disorders due to expected light-tissue interaction. This type of therapy may help to improve muscular oxygenation, thereby increasing aerobic fitness and functional capacity. This study is a randomized, double-blind, placebo-controlled crossover trial approved by the Ethics Committee of the Federal University of São Carlos and registered at ClinicalTrials.gov. Four separate tests will be performed to evaluate the acute effect of phototherapy. All participants will receive both interventions in random order: light-emitting diode therapy (LEDT) and placebo, with a minimum 14-day interval between sessions (washout period). Immediately after the intervention, participants will perform moderate constant workload cycling exercise corresponding to 80 % of the pulmonary oxygen uptake [Formula: see text] during the gas exchange threshold (GET). LEDT will be administered with a multidiode cluster probe (50 GaAIA LEDs, 850 ηm, 75 mW each diode, and 3 J per point) before each exercise session. Pulmonary oxygen uptake, muscle oxygenation, heart rate, and arterial pressure will be measured using a computerized metabolic cart, a near-infrared spectrometer, an electrocardiogram, and a photoplethysmography system, respectively. The main objective of this study is to evaluate the acute effects of muscular pre-conditioning using LED phototherapy on pulmonary oxygen uptake, muscle oxygenation, heart rate, and arterial pressure dynamics during dynamic moderate exercise. We hypothesize that phototherapy may be beneficial to optimize aerobic fitness in the DM population. Data will be published after the study is completed. Registered at ClinicalTrials.gov under trial number NCT01889784 (date of registration 5 June 2013).

[Mechanism of the decrease in basal metabolism during adaptation to hypoxia].

PubMed

Meerson, F Z; Bogomolov, A F

1978-09-01

Oxygen uptake fell by 40% in rat adaptation to the periodic action of hypoxia under conditions of pressure chamber. This phenomenon did not disappear in animals in the state of profound anesthesia, and, consequently, was independent of adaptation changes of the cortical regulation of the animal motor activity. A cut of oxygen uptake by half persisted with the action of cold, noradrenaline, and 2,4-dinitrophenol, uncoupling oxidation and phosphorylation, on the organism. Thus, economic expenditure of oxygen in hypoxia adaptation could not be fully explained by increase of oxydation and phosphorylation conjugation.

Evaluation of Optimum Moisture Content for Composting of Beef Manure and Bedding Material Mixtures Using Oxygen Uptake Measurement

PubMed Central

Kim, Eunjong; Lee, Dong-Hyun; Won, Seunggun; Ahn, Heekwon

2016-01-01

Moisture content influences physiological characteristics of microbes and physical structure of solid matrices during composting of animal manure. If moisture content is maintained at a proper level, aerobic microorganisms show more active oxygen consumption during composting due to increased microbial activity. In this study, optimum moisture levels for composting of two bedding materials (sawdust, rice hull) and two different mixtures of bedding and beef manure (BS, Beef cattle manure+sawdust; BR, Beef cattle manure+rice hull) were determined based on oxygen uptake rate measured by a pressure sensor method. A broad range of oxygen uptake rates (0.3 to 33.3 mg O2/g VS d) were monitored as a function of moisture level and composting feedstock type. The maximum oxygen consumption of each material was observed near the saturated condition, which ranged from 75% to 98% of water holding capacity. The optimum moisture content of BS and BR were 70% and 57% on a wet basis, respectively. Although BS’s optimum moisture content was near saturated state, its free air space kept a favorable level (above 30%) for aerobic composting due to the sawdust’s coarse particle size and bulking effect. PMID:26954138

Evaluation of Optimum Moisture Content for Composting of Beef Manure and Bedding Material Mixtures Using Oxygen Uptake Measurement.

PubMed

Kim, Eunjong; Lee, Dong-Hyun; Won, Seunggun; Ahn, Heekwon

2016-05-01

Moisture content influences physiological characteristics of microbes and physical structure of solid matrices during composting of animal manure. If moisture content is maintained at a proper level, aerobic microorganisms show more active oxygen consumption during composting due to increased microbial activity. In this study, optimum moisture levels for composting of two bedding materials (sawdust, rice hull) and two different mixtures of bedding and beef manure (BS, Beef cattle manure+sawdust; BR, Beef cattle manure+rice hull) were determined based on oxygen uptake rate measured by a pressure sensor method. A broad range of oxygen uptake rates (0.3 to 33.3 mg O2/g VS d) were monitored as a function of moisture level and composting feedstock type. The maximum oxygen consumption of each material was observed near the saturated condition, which ranged from 75% to 98% of water holding capacity. The optimum moisture content of BS and BR were 70% and 57% on a wet basis, respectively. Although BS's optimum moisture content was near saturated state, its free air space kept a favorable level (above 30%) for aerobic composting due to the sawdust's coarse particle size and bulking effect.

Comparative analysis of nitrite uptake and hemoglobin-nitrite reactions in erythrocytes: sorting out uptake mechanisms and oxygenation dependencies.

PubMed

Jensen, Frank B; Rohde, Sabina

2010-04-01

Nitrite uptake into red blood cells (RBCs) precedes its intracellular reactions with hemoglobin (Hb) that forms nitric oxide (NO) during hypoxia. We investigated the uptake of nitrite and its reactions with Hb at different oxygen saturations (So(2)), using RBCs with (carp and rabbit) and without (hagfish and lamprey) anion exchanger-1 (AE1) in the membrane, with the aim to unravel the mechanisms and oxygenation dependencies of nitrite transport. Added nitrite rapidly diffused into the RBCs until equilibrium. The distribution ratio of nitrite across the membrane agreed with that expected from HNO(2) diffusion and AE1-mediated facilitated NO(2)(-) diffusion. Participation of HNO(2) diffusion was emphasized by rapid transmembrane nitrite equilibration also in the natural AE1 knockouts. Following the equilibration, nitrite was consumed by reacting with Hb, which created a continued inward diffusion controlled by intracellular reaction rates. Changes in nitrite uptake with So(2), pH, or species were accordingly explained by corresponding changes in reaction rates. In carp, nitrite uptake rates increased linearly with decreasing So(2) over the entire So(2) range. In rabbit, nitrite uptake rates were highest at intermediate So(2), producing a bell-shaped relationship with So(2). Nitrite consumption increased approximately 10-fold with a 1 unit decrease in pH, as expected from the involvement of protons in the reactions with Hb. The reaction of nitrite with deoxyhemoglobin was favored over that with oxyhemoglobin at intermediate So(2). We propose a model for RBC nitrite uptake that involves both HNO(2) diffusion and AE1-mediated transport and that explains both the present and previous (sometimes puzzling) results.

Brain oxygen utilization is unchanged by hypoglycemia in normal humans: lactate, alanine, and leucine uptake are not sufficient to offset energy deficit.

PubMed

Lubow, Jeffrey M; Piñón, Ivan G; Avogaro, Angelo; Cobelli, Claudio; Treeson, David M; Mandeville, Katherine A; Toffolo, Gianna; Boyle, Patrick J

2006-01-01

During hypoglycemia, substrates other than glucose have been suggested to serve as alternate neural fuels. We evaluated brain uptake of endogenously produced lactate, alanine, and leucine at euglycemia and during insulin-induced hypoglycemia in 17 normal subjects. Cross-brain arteriovenous differences for plasma glucose, lactate, alanine, leucine, and oxygen content were quantitated. Cerebral blood flow (CBF) was measured by Fick methodology using N(2)O as the dilution indicator gas. Substrate uptake was measured as the product of CBF and the arteriovenous concentration difference. As arterial glucose concentration fell, cerebral oxygen utilization and CBF remained unchanged. Brain glucose uptake (BGU) decreased from 36.3+/-2.6 to 26.6+/-2.1 micromol.100 g of brain(-1).min(-1) (P<0.001), equivalent to a drop in ATP of 291 micromol.100 g(-1).min(-1). Arterial lactate rose (P<0.001), whereas arterial alanine and leucine fell (P<0.009 and P<0.001, respectively). Brain lactate uptake (BLU) increased from a net release of -1.8+/- 0.6 to a net uptake of 2.5+/-1.2 micromol.100 g(-1).min(-1) (P<0.001), equivalent to an increase in ATP of 74 micromol.100 g(-1).min(-1). Brain leucine uptake decreased from 7.1+/-1.2 to 2.5 +/- 0.5 micromol.100 g(-1).min(-1) (P<0.001), and brain alanine uptake trended downward (P<0.08). We conclude that the ATP generated from the physiological increase in BLU during hypoglycemia accounts for no more than 25% of the brain glucose energy deficit.

Measuring Steady-State Oxygen Uptake during the 6-Min Walk Test in Adults with Cerebral Palsy: Feasibility and Construct Validity

ERIC Educational Resources Information Center

Maltais, Desiree B.; Robitaille, Nancy-Michelle; Dumas, Francine; Boucher, Normand; Richards, Carol L.

2012-01-01

This study evaluated the feasibility of measuring steady-state oxygen uptake (V[Combining Dot Above]O[subscript 2]) during the 6-min walk test (6MWT) in adults with cerebral palsy (CP) who walk without support and whether there is construct validity for net 6MWT V[Combining Dot Above]O[subscript 2] as a measure of their walking ability.…

Loss of Brain Aerobic Glycolysis in Normal Human Aging.

PubMed

Goyal, Manu S; Vlassenko, Andrei G; Blazey, Tyler M; Su, Yi; Couture, Lars E; Durbin, Tony J; Bateman, Randall J; Benzinger, Tammie L-S; Morris, John C; Raichle, Marcus E

2017-08-01

The normal aging human brain experiences global decreases in metabolism, but whether this affects the topography of brain metabolism is unknown. Here we describe PET-based measurements of brain glucose uptake, oxygen utilization, and blood flow in cognitively normal adults from 20 to 82 years of age. Age-related decreases in brain glucose uptake exceed that of oxygen use, resulting in loss of brain aerobic glycolysis (AG). Whereas the topographies of total brain glucose uptake, oxygen utilization, and blood flow remain largely stable with age, brain AG topography changes significantly. Brain regions with high AG in young adults show the greatest change, as do regions with prolonged developmental transcriptional features (i.e., neoteny). The normal aging human brain thus undergoes characteristic metabolic changes, largely driven by global loss and topographic changes in brain AG. Copyright © 2017 Elsevier Inc. All rights reserved.

Walking efficiency before and after total hip replacement.

PubMed

Brown, M; Hislop, H J; Waters, R L; Porell, D

1980-10-01

The energy cost of walking and gait characteristics of patients with hip disease were studied to determine changes in walking efficiency following total hip replacement. Twenty-nine patients, 24 with unilateral hip disease and 5 with bilateral hip disease, were tested preoperatively and at various times postoperatively. Oxygen uptake was measured by a modified Douglas bag procedure. The temporal and distance characteristics of gait were measured with contact closing heel switches. Results showed postoperative increases in velocity, cadence, and stride length in patients with unilateral disease and with bilateral disease with bilateral replacement. After surgery, energy cost tended toward more normal levels, but the subjects were not within normal limits for oxygen uptake per minute, oxygen uptake per distance walked, or percent of predicted maximum aerobic capacity. Comparison of energy expenditure data with temporal and distance factors of gait indicated that all subjects became more physiologically efficient after hip replacement.

Oxygen uptake kinetics of constant-load work - Upright vs. supine exercise

NASA Technical Reports Server (NTRS)

Convertino, V. A.; Goldwater, D. J.; Sandler, H.

1984-01-01

Supine and upright positions were used in a comparitive study of the effects of constant load exercise on oxygen uptake (VO2), O2 deficit, steady-state VO2 and VO2 following recovery from constant load work. Ten male subjects (36-40 yr.) performed one submaximal exercise test in the supine and one test in the upright position consisting of 5 min rest and 5 min cycle ergometer exercise at 700 kg/min followed by ten minutes of recovery. It is found that the significant difference in VO2 kinetics during exercise in the upright compared to supine position resulted from changes in oxygen transport and utilization mechanisms rather than changes in mechanical efficiency. To the extent that data measured in the supine position can be used to estimate physiological responses to zero gravity, it is suggested that limitation of systemic O2 consumption may be the result of slow rates of oxygen uptake during transient periods of muscular work. Significant reductions in the rate of steady-state VO2 attainment at submaximal work intensities may produce an onset of muscle fatigue and exhaustion.

Hydrogen Peroxide-Dependent Uptake of Iodine by Marine Flavobacteriaceae Bacterium Strain C-21▿

PubMed Central

Amachi, Seigo; Kimura, Koh; Muramatsu, Yasuyuki; Shinoyama, Hirofumi; Fujii, Takaaki

2007-01-01

The cells of the marine bacterium strain C-21, which is phylogenetically closely related to Arenibacter troitsensis, accumulate iodine in the presence of glucose and iodide (I−). In this study, the detailed mechanism of iodine uptake by C-21 was determined using a radioactive iodide tracer, 125I−. In addition to glucose, oxygen and calcium ions were also required for the uptake of iodine. The uptake was not inhibited or was only partially inhibited by various metabolic inhibitors, whereas reducing agents and catalase strongly inhibited the uptake. When exogenous glucose oxidase was added to the cell suspension, enhanced uptake of iodine was observed. The uptake occurred even in the absence of glucose and oxygen if hydrogen peroxide was added to the cell suspension. Significant activity of glucose oxidase was found in the crude extracts of C-21, and it was located mainly in the membrane fraction. These findings indicate that hydrogen peroxide produced by glucose oxidase plays a key role in the uptake of iodine. Furthermore, enzymatic oxidation of iodide strongly stimulated iodine uptake in the absence of glucose. Based on these results, the mechanism was considered to consist of oxidation of iodide to hypoiodous acid by hydrogen peroxide, followed by passive translocation of this uncharged iodine species across the cell membrane. Interestingly, such a mechanism of iodine uptake is similar to that observed in iodine-accumulating marine algae. PMID:17933915

Case-Based Learning of Blood Oxygen Transport

ERIC Educational Resources Information Center

Cliff, William H.

2006-01-01

A case study about carbon monoxide poisoning was used help students gain a greater understanding of the physiology of oxygen transport by the blood. A review of student answers to the case questions showed that students can use the oxygen-hemoglobin dissociation curve to make meaningful determinations of oxygen uptake and delivery. However, the…

Computer program for calculation of oxygen uptake

NASA Technical Reports Server (NTRS)

Castle, B. L.; Castle, G.; Greenleaf, J. E.

1979-01-01

A description and operational precedures are presented for a computer program, written in Super Basic, that calculates oxygen uptake, carbon dioxide production, and related ventilation parameters. Program features include: (1) the option of entering slope and intercept values of calibration curves for the O2 and CO2 and analyzers; (2) calculation of expired water vapor pressure; and (3) the option of entering inspured O2 and CO2 concentrations. The program is easily adaptable for programmable laboratory calculators.

Measuring oxygen uptake in fishes with bimodal respiration.

PubMed

Lefevre, S; Bayley, M; McKenzie, D J

2016-01-01

Respirometry is a robust method for measurement of oxygen uptake as a proxy for metabolic rate in fishes, and how species with bimodal respiration might meet their demands from water v. air has interested researchers for over a century. The challenges of measuring oxygen uptake from both water and air, preferably simultaneously, have been addressed in a variety of ways, which are briefly reviewed. These methods are not well-suited for the long-term measurements necessary to be certain of obtaining undisturbed patterns of respiratory partitioning, for example, to estimate traits such as standard metabolic rate. Such measurements require automated intermittent-closed respirometry that, for bimodal fishes, has only recently been developed. This paper describes two approaches in enough detail to be replicated by the interested researcher. These methods are for static respirometry. Measuring oxygen uptake by bimodal fishes during exercise poses specific challenges, which are described to aid the reader in designing experiments. The respiratory physiology and behaviour of air-breathing fishes is very complex and can easily be influenced by experimental conditions, and some general considerations are listed to facilitate the design of experiments. Air breathing is believed to have evolved in response to aquatic hypoxia and, probably, associated hypercapnia. The review ends by considering what realistic hypercapnia is, how hypercapnic tropical waters can become and how this might influence bimodal animals' gas exchange. © 2015 The Fisheries Society of the British Isles.

Cell line-dependent differences in uptake and retention of the hypoxia-selective nuclear imaging agent Cu-ATSM.

PubMed

Burgman, Paul; O'Donoghue, Joseph A; Lewis, Jason S; Welch, Michael J; Humm, John L; Ling, C Clifton

2005-08-01

Cu-diacetyl-bis(N(4)-methylthiosemicarbazone) [Cu-ATSM] is a potential marker for tumor hypoxia that has been under evaluation for clinical use. In this study, we examined the mechanisms underlying the uptake of (64)Cu in cells incubated with (64)Cu-ATSM. The in vitro uptake of (64)Cu was determined as a function of oxygenation conditions and incubation time with (64)Cu-ATSM using four and two tumor cell lines of human origin and rodent origin, respectively. Additionally, the rate of (64)Cu efflux and Cu-ATSM metabolism was determined. (64)Cu accumulation is rapid during the first 0.5-1 h of incubation. It is highest in anoxic cells but is also significant in normoxic cells. After this initial period, the level of intracellular (64)Cu varies depending on the cell line and the oxygenation conditions and, in some circumstances, may decrease. During the first 0.5-1 h, the ratio of (64)Cu levels between anoxic and normoxic cells is approximately 2:10 and that between hypoxic (0.5% O(2)) and normoxic cells is approximately 1:2.5, depending on the cell line. These ratios generally decrease at longer times. The (64)Cu-ATSM compound was found to be metabolized during incubation in a manner dependent on oxygenation conditions. Within 2 h under anoxic conditions, (64)Cu-ATSM could no longer be detected, although 60-90% of the amount of (64)Cu added as (64)Cu-ATSM was present in the medium. Non-ATSM (64)Cu was taken up by the cells, albeit at a much slower rate. Efflux rates of (64)Cu were found to be cell line dependent and appeared to be inversely correlated with the final (64)Cu uptake levels under anoxic conditions. The uptake and retention of (64)Cu and their relation to oxygenation conditions were found to be cell line dependent. Given the complexities in the oxygen dependence and cell line-dependent kinetics of uptake and retention of Cu following exposure to Cu-ATSM, the clinical utility of this compound may be disease site specific.

Optimal villi density for maximal oxygen uptake in the human placenta.

PubMed

Serov, A S; Salafia, C M; Brownbill, P; Grebenkov, D S; Filoche, M

2015-01-07

We present a stream-tube model of oxygen exchange inside a human placenta functional unit (a placentone). The effect of villi density on oxygen transfer efficiency is assessed by numerically solving the diffusion-convection equation in a 2D+1D geometry for a wide range of villi densities. For each set of physiological parameters, we observe the existence of an optimal villi density providing a maximal oxygen uptake as a trade-off between the incoming oxygen flow and the absorbing villus surface. The predicted optimal villi density 0.47±0.06 is compatible to previous experimental measurements. Several other ways to experimentally validate the model are also proposed. The proposed stream-tube model can serve as a basis for analyzing the efficiency of human placentas, detecting possible pathologies and diagnosing placental health risks for newborns by using routine histology sections collected after birth. Copyright © 2014 Elsevier Ltd. All rights reserved.

Predicting Blood Lactate Concentration and Oxygen Uptake from sEMG Data during Fatiguing Cycling Exercise.

PubMed

Ražanskas, Petras; Verikas, Antanas; Olsson, Charlotte; Viberg, Per-Arne

2015-08-19

This article presents a study of the relationship between electromyographic (EMG) signals from vastus lateralis, rectus femoris, biceps femoris and semitendinosus muscles, collected during fatiguing cycling exercises, and other physiological measurements, such as blood lactate concentration and oxygen consumption. In contrast to the usual practice of picking one particular characteristic of the signal, e.g., the median or mean frequency, multiple variables were used to obtain a thorough characterization of EMG signals in the spectral domain. Based on these variables, linear and non-linear (random forest) models were built to predict blood lactate concentration and oxygen consumption. The results showed that mean and median frequencies are sub-optimal choices for predicting these physiological quantities in dynamic exercises, as they did not exhibit significant changes over the course of our protocol and only weakly correlated with blood lactate concentration or oxygen uptake. Instead, the root mean square of the original signal and backward difference, as well as parameters describing the tails of the EMG power distribution were the most important variables for these models. Coefficients of determination ranging from R(2) = 0:77 to R(2) = 0:98 (for blood lactate) and from R(2) = 0:81 to R(2) = 0:97 (for oxygen uptake) were obtained when using random forest regressors.

Aerobic Interval vs. Continuous Training in Patients with Coronary Artery Disease or Heart Failure: An Updated Systematic Review and Meta-Analysis with a Focus on Secondary Outcomes.

PubMed

Pattyn, Nele; Beulque, Randy; Cornelissen, Véronique

2018-05-01

In a previous meta-analysis including nine trials comparing aerobic interval training with aerobic continuous training in patients with coronary artery disease, we found a significant difference in peak oxygen uptake favoring aerobic interval training. The objective of this study was to (1) update the original meta-analysis focussing on peak oxygen uptake and (2) evaluate the effect on secondary outcomes. We conducted a systematic review with a meta-analysis by searching PubMed and SPORTDiscus databases up to March 2017. We included randomized trials comparing aerobic interval training and aerobic continuous training in patients with coronary artery disease or chronic heart failure. The primary outcome was change in peak oxygen uptake. Secondary outcomes included cardiorespiratory parameters, cardiovascular risk factors, cardiac and vascular function, and quality of life. Twenty-four papers were identified (n = 1080; mean age 60.7 ± 10.7 years). Aerobic interval training resulted in a higher increase in peak oxygen uptake compared with aerobic continuous training in all patients (1.40 mL/kg/min; p < 0.001), and in the subgroups of patients with coronary artery disease (1.25 mL/kg/min; p = 0.001) and patients with chronic heart failure with reduced ejection fraction (1.46 mL/kg/min; p = 0.03). Moreover, a larger increase of the first ventilatory threshold and peak heart rate was observed after aerobic interval training in all patients. Other cardiorespiratory parameters, cardiovascular risk factors, and quality of life were equally affected. This meta-analysis adds further evidence to the clinically significant larger increase in peak oxygen uptake following aerobic interval training vs. aerobic continuous training in patients with coronary artery disease and chronic heart failure. More well-designed randomized controlled trials are needed to establish the safety of aerobic interval training and the sustainability of the training response over longer periods.

An emerging role for gasotransmitters in the control of breathing and ionic regulation in fish.

PubMed

Perry, Steve; Kumai, Y; Porteus, C S; Tzaneva, V; Kwong, R W M

2016-02-01

Three gases comprising nitric oxide, carbon monoxide and hydrogen sulphide, collectively are termed gasotransmitters. The gasotransmitters control several physiological functions in fish by acting as intracellular signaling molecules. Hydrogen sulphide, first implicated in vasomotor control in fish, plays a critical role in oxygen chemoreception owing to its production and downstream effects within the oxygen chemosensory cells, the neuroepithelial cells. Indeed, there is emerging evidence that hydrogen sulphide may contribute to oxygen sensing in both fish and mammals by promoting membrane depolarization of the chemosensory cells. Unlike hydrogen sulphide which stimulates breathing in zebrafish, carbon monoxide inhibits ventilation in goldfish and zebrafish whereas nitric oxide stimulates breathing in zebrafish larvae while inhibiting breathing in adults. Gasotransmitters also modulate ionic uptake in zebrafish. Though nothing is known about the role of CO, reduced activities of branchial Na(+)/K(+)-ATPase and H(+)-ATPase activities in the presence of NO donors suggest an inhibitory role of NO in fish osmoregulation. Hydrogen sulphide inhibits Na(+) uptake in zebrafish larvae and contributes to lowering Na(+) uptake capacity in fish acclimated to Na(+)-enriched water whereas it stimulates Ca(2+) uptake in larvae exposed to Ca(2+)-poor water.

Simultaneous quantum yield measurements of carbon uptake and oxygen evolution in microalgal cultures

PubMed Central

Gholami, Pardis; Kline, David I.; DuPont, Christopher L.; Dickson, Andrew G.; Mendola, Dominick; Martz, Todd; Allen, Andrew E.; Mitchell, B. Greg

2018-01-01

The photosynthetic quantum yield (Φ), defined as carbon fixed or oxygen evolved per unit of light absorbed, is a fundamental but rarely determined biophysical parameter. A method to estimate Φ for both net carbon uptake and net oxygen evolution simultaneously can provide important insights into energy and mass fluxes. Here we present details for a novel system that allows quantification of carbon fluxes using pH oscillation and simultaneous oxygen fluxes by integration with a membrane inlet mass spectrometer. The pHOS system was validated using Phaeodactylum tricornutum cultured with continuous illumination of 110 μmole quanta m-2 s-1 at 25°C. Furthermore, simultaneous measurements of carbon and oxygen flux using the pHOS-MIMS and photon flux based on spectral absorption were carried out to explore the kinetics of Φ in P. tricornutum during its acclimation from low to high light (110 to 750 μmole quanta m-2 s-1). Comparing results at 0 and 24 hours, we observed strong decreases in cellular chlorophyll a (0.58 to 0.21 pg cell-1), Fv/Fm (0.71 to 0.59) and maximum ΦCO2 (0.019 to 0.004) and ΦO2 (0.028 to 0.007), confirming the transition toward high light acclimation. The Φ time-series indicated a non-synchronized acclimation response between carbon uptake and oxygen evolution, which has been previously inferred based on transcriptomic changes for a similar experimental design with the same diatom that lacked physiological data. The integrated pHOS-MIMS system can provide simultaneous carbon and oxygen measurements accurately, and at the time-resolution required to resolve high-resolution carbon and oxygen physiological dynamics. PMID:29920568

Plasma /Na+/, /Ca++/, and volume shifts and thermoregulation during exercise in man

NASA Technical Reports Server (NTRS)

Greenleaf, J. E.; Convertino, V. A.; Stremel, R. W.; Bernauer, E. M.; Adams, W. C.; Vignau, S. R.; Brock, P. J.

1977-01-01

Graded-exercise experiments are conducted on six trained male runners (19-23 yr) subjected to ergometer exercise in a program consisting of 30-min resting control period, 60 min of rest or exercise at work loads that resulted in a maximal oxygen uptake equivalent to 6% (resting), 23%, 43%, and 62% of maximal oxygen uptake, followed by 30 min of recovery. The parameters measured and discussed are rectal temperature (T-re), skin temperatures at different spots, maximal oxygen uptake, plasma volume (PV), and various plasma electrolyte and protein concentrations. The objectives are to determine whether the increased T-re during progressively greater work loads are related to plasma sodium ion and calcium ion concentrations, as well as to evaluate the influence of PV shifts on the electrolyte and osmotic concentrations. The results suggest that the shift (loss) in PV accounts for the increases in the plasma constituent concentrations that result in significant correlations with T-re.

The oxygen uptake slow component at submaximal intensities in breaststroke swimming

PubMed Central

Oliveira, Diogo R.; Gonçalves, Lio F.; Reis, António M.; Fernandes, Ricardo J.; Garrido, Nuno D.

2016-01-01

Abstract The present work proposed to study the oxygen uptake slow component (VO2 SC) of breaststroke swimmers at four different intensities of submaximal exercise, via mathematical modeling of a multi-exponential function. The slow component (SC) was also assessed with two different fixed interval methods and the three methods were compared. Twelve male swimmers performed a test comprising four submaximal 300 m bouts at different intensities where all expired gases were collected breath by breath. Multi-exponential modeling showed values above 450 ml·min−1 of the SC in the two last bouts of exercise (those with intensities above the lactate threshold). A significant effect of the method that was used to calculate the VO2 SC was revealed. Higher mean values were observed when using mathematical modeling compared with the fixed interval 3rd min method (F=7.111; p=0.012; η2=0.587); furthermore, differences were detected among the two fixed interval methods. No significant relationship was found between the SC determined by any method and the blood lactate measured at each of the four exercise intensities. In addition, no significant association between the SC and peak oxygen uptake was found. It was concluded that in trained breaststroke swimmers, the presence of the VO2 SC may be observed at intensities above that corresponding to the 3.5 mM-1 threshold. Moreover, mathematical modeling of the oxygen uptake on-kinetics tended to show a higher slow component as compared to fixed interval methods. PMID:28149379

Anaerobic and Aerobic Performance of Elite Female and Male Snowboarders

PubMed Central

Żebrowska, Aleksandra; Żyła, Dorota; Kania, Damian; Langfort, Józef

2012-01-01

The physiological adaptation to training is specific to the muscle activity, dominant energy system involved, muscle groups trained, as well as intensity and volume of training. Despite increasing popularity of snowboarding only little scientific data is available on the physiological characteristics of female and male competitive snowboarders. Therefore, the purpose of this study was to compare the aerobic capacity and maximal anaerobic power of elite Polish snowboarders with untrained subjects. Ten snowboarders and ten aged matched students of Physical Education performed two exercise tests. First, a 30-second Wingate test was conducted and next, a cycle ergometer exercise test with graded intensity. In the first test, peak anaerobic power, the total work, relative peak power and relative mean power were measured. During the second test, relative maximal oxygen uptake and lactate threshold were evaluated. There were no significant differences in absolute and relative maximal oxygen uptake between snowboarders and the control group. Mean maximal oxygen uptake and lactate threshold were significantly higher in men than in women. Significant differences were found between trained men and women regarding maximal power and relative maximal power. The elite snowboarders demonstrated a high level of anaerobic power. The level of relative peak power in trained women correlated negatively with maximal oxygen uptake. In conclusion, our results seem to indicate that the demanding competition program of elite snowboarders provides a significant training stimulus mainly for anaerobic power with minor changes in anaerobic performance. PMID:23487498

Oxygen Uptake Efficiency Plateau Best Predicts Early Death in Heart Failure

PubMed Central

Hansen, James E.; Stringer, William W.

2012-01-01

Background: The responses of oxygen uptake efficiency (ie, oxygen uptake/ventilation = V˙o2/V˙e) and its highest plateau (OUEP) during incremental cardiopulmonary exercise testing (CPET) in patients with chronic left heart failure (HF) have not been previously reported. We planned to test the hypothesis that OUEP during CPET is the best single predictor of early death in HF. Methods: We evaluated OUEP, slope of V˙o2 to log(V˙e) (oxygen uptake efficiency slope), oscillatory breathing, and all usual resting and CPET measurements in 508 patients with low-ejection-fraction (< 35%) HF. Each had further evaluations at other sites, including cardiac catheterization. Outcomes were 6-month all-reason mortality and morbidity (death or > 24 h cardiac hospitalization). Statistical analyses included area under curve of receiver operating characteristics, ORs, univariate and multivariate Cox regression, and Kaplan-Meier plots. Results: OUEP, which requires only moderate exercise, was often reduced in patients with HF. A low % predicted OUEP was the single best predictor of mortality (P < .0001), with an OR of 13.0 (P < .001). When combined with oscillatory breathing, the OR increased to 56.3, superior to all other resting or exercise parameters or combinations of parameters. Other statistical analyses and morbidity analysis confirmed those findings. Conclusions: OUEP is often reduced in patients with HF. Low % predicted OUEP (< 65% predicted) is the single best predictor of early death, better than any other CPET or other cardiovascular measurement. Paired with oscillatory breathing, it is even more powerful. PMID:22030802

Maximum Plant Uptakes for Water, Nutrients, and Oxygen Are Not Always Met by Irrigation Rate and Distribution in Water-based Cultivation Systems.

PubMed

Blok, Chris; Jackson, Brian E; Guo, Xianfeng; de Visser, Pieter H B; Marcelis, Leo F M

2017-01-01

Growing on rooting media other than soils in situ -i.e., substrate-based growing- allows for higher yields than soil-based growing as transport rates of water, nutrients, and oxygen in substrate surpass those in soil. Possibly water-based growing allows for even higher yields as transport rates of water and nutrients in water surpass those in substrate, even though the transport of oxygen may be more complex. Transport rates can only limit growth when they are below a rate corresponding to maximum plant uptake. Our first objective was to compare Chrysanthemum growth performance for three water-based growing systems with different irrigation. We compared; multi-point irrigation into a pond (DeepFlow); one-point irrigation resulting in a thin film of running water (NutrientFlow) and multi-point irrigation as droplets through air (Aeroponic). Second objective was to compare press pots as propagation medium with nutrient solution as propagation medium. The comparison included DeepFlow water-rooted cuttings with either the stem 1 cm into the nutrient solution or with the stem 1 cm above the nutrient solution. Measurements included fresh weight, dry weight, length, water supply, nutrient supply, and oxygen levels. To account for differences in radiation sum received, crop performance was evaluated with Radiation Use Efficiency (RUE) expressed as dry weight over sum of Photosynthetically Active Radiation. The reference, DeepFlow with substrate-based propagation, showed the highest RUE, even while the oxygen supply provided by irrigation was potentially growth limiting. DeepFlow with water-based propagation showed 15-17% lower RUEs than the reference. NutrientFlow showed 8% lower RUE than the reference, in combination with potentially limiting irrigation supply of nutrients and oxygen. Aeroponic showed RUE levels similar to the reference and Aeroponic had non-limiting irrigation supply of water, nutrients, and oxygen. Water-based propagation affected the subsequent cultivation in the DeepFlow negatively compared to substrate-based propagation. Water-based propagation resulted in frequent transient discolorations after transplanting in all cultivation systems, indicating a factor, other than irrigation supply of water, nutrients, and oxygen, influencing plant uptake. Plant uptake rates for water, nutrients, and oxygen are offered as a more fundamental way to compare and improve growing systems.

Maximum Plant Uptakes for Water, Nutrients, and Oxygen Are Not Always Met by Irrigation Rate and Distribution in Water-based Cultivation Systems

PubMed Central

Blok, Chris; Jackson, Brian E.; Guo, Xianfeng; de Visser, Pieter H. B.; Marcelis, Leo F. M.

2017-01-01

Growing on rooting media other than soils in situ -i.e., substrate-based growing- allows for higher yields than soil-based growing as transport rates of water, nutrients, and oxygen in substrate surpass those in soil. Possibly water-based growing allows for even higher yields as transport rates of water and nutrients in water surpass those in substrate, even though the transport of oxygen may be more complex. Transport rates can only limit growth when they are below a rate corresponding to maximum plant uptake. Our first objective was to compare Chrysanthemum growth performance for three water-based growing systems with different irrigation. We compared; multi-point irrigation into a pond (DeepFlow); one-point irrigation resulting in a thin film of running water (NutrientFlow) and multi-point irrigation as droplets through air (Aeroponic). Second objective was to compare press pots as propagation medium with nutrient solution as propagation medium. The comparison included DeepFlow water-rooted cuttings with either the stem 1 cm into the nutrient solution or with the stem 1 cm above the nutrient solution. Measurements included fresh weight, dry weight, length, water supply, nutrient supply, and oxygen levels. To account for differences in radiation sum received, crop performance was evaluated with Radiation Use Efficiency (RUE) expressed as dry weight over sum of Photosynthetically Active Radiation. The reference, DeepFlow with substrate-based propagation, showed the highest RUE, even while the oxygen supply provided by irrigation was potentially growth limiting. DeepFlow with water-based propagation showed 15–17% lower RUEs than the reference. NutrientFlow showed 8% lower RUE than the reference, in combination with potentially limiting irrigation supply of nutrients and oxygen. Aeroponic showed RUE levels similar to the reference and Aeroponic had non-limiting irrigation supply of water, nutrients, and oxygen. Water-based propagation affected the subsequent cultivation in the DeepFlow negatively compared to substrate-based propagation. Water-based propagation resulted in frequent transient discolorations after transplanting in all cultivation systems, indicating a factor, other than irrigation supply of water, nutrients, and oxygen, influencing plant uptake. Plant uptake rates for water, nutrients, and oxygen are offered as a more fundamental way to compare and improve growing systems. PMID:28443129

Roles of sulfuric acid in elemental mercury removal by activated carbon and sulfur-impregnated activated carbon.

PubMed

Morris, Eric A; Kirk, Donald W; Jia, Charles Q; Morita, Kazuki

2012-07-17

This work addresses the discrepancy in the literature regarding the effects of sulfuric acid (H(2)SO(4)) on elemental Hg uptake by activated carbon (AC). H(2)SO(4) in AC substantially increased Hg uptake by absorption particularly in the presence of oxygen. Hg uptake increased with acid amount and temperature exceeding 500 mg-Hg/g-AC after 3 days at 200 °C with AC treated with 20% H(2)SO(4). In the absence of other strong oxidizers, oxygen was able to oxidize Hg. Upon oxidation, Hg was more readily soluble in the acid, greatly enhancing its uptake by acid-treated AC. Without O(2), S(VI) in H(2)SO(4) was able to oxidize Hg, thus making it soluble in H(2)SO(4). Consequently, the presence of a bulk H(2)SO(4) phase within AC pores resulted in an orders of magnitude increase in Hg uptake capacity. However, the bulk H(2)SO(4) phase lowered the AC pore volume and could block the access to the active surface sites and potentially hinder Hg uptake kinetics. AC treated with SO(2) at 700 °C exhibited a much faster rate of Hg uptake attributed to sulfur functional groups enhancing adsorption kinetics. SO(2)-treated carbon maintained its fast uptake kinetics even after impregnation by 20% H(2)SO(4).

GEDAE-LaB: A Free Software to Calculate the Energy System Contributions during Exercise

PubMed Central

Bertuzzi, Rômulo; Melegati, Jorge; Bueno, Salomão; Ghiarone, Thaysa; Pasqua, Leonardo A.; Gáspari, Arthur Fernandes; Lima-Silva, Adriano E.; Goldman, Alfredo

2016-01-01

Purpose The aim of the current study is to describe the functionality of free software developed for energy system contributions and energy expenditure calculation during exercise, namely GEDAE-LaB. Methods Eleven participants performed the following tests: 1) a maximal cycling incremental test to measure the ventilatory threshold and maximal oxygen uptake (V˙O2max); 2) a cycling workload constant test at moderate domain (90% ventilatory threshold); 3) a cycling workload constant test at severe domain (110% V˙O2max). Oxygen uptake and plasma lactate were measured during the tests. The contributions of the aerobic (AMET), anaerobic lactic (LAMET), and anaerobic alactic (ALMET) systems were calculated based on the oxygen uptake during exercise, the oxygen energy equivalents provided by lactate accumulation, and the fast component of excess post-exercise oxygen consumption, respectively. In order to assess the intra-investigator variation, four different investigators performed the analyses independently using GEDAE-LaB. A direct comparison with commercial software was also provided. Results All subjects completed 10 min of exercise at moderate domain, while the time to exhaustion at severe domain was 144 ± 65 s. The AMET, LAMET, and ALMET contributions during moderate domain were about 93, 2, and 5%, respectively. The AMET, LAMET, and ALMET contributions during severe domain were about 66, 21, and 13%, respectively. No statistical differences were found between the energy system contributions and energy expenditure obtained by GEDAE-LaB and commercial software for both moderate and severe domains (P > 0.05). The ICC revealed that these estimates were highly reliable among the four investigators for both moderate and severe domains (all ICC ≥ 0.94). Conclusion These findings suggest that GEDAE-LaB is a free software easily comprehended by users minimally familiarized with adopted procedures for calculations of energetic profile using oxygen uptake and lactate accumulation during exercise. By providing availability of the software and its source code we hope to facilitate future related research. PMID:26727499

GEDAE-LaB: A Free Software to Calculate the Energy System Contributions during Exercise.

PubMed

Bertuzzi, Rômulo; Melegati, Jorge; Bueno, Salomão; Ghiarone, Thaysa; Pasqua, Leonardo A; Gáspari, Arthur Fernandes; Lima-Silva, Adriano E; Goldman, Alfredo

2016-01-01

The aim of the current study is to describe the functionality of free software developed for energy system contributions and energy expenditure calculation during exercise, namely GEDAE-LaB. Eleven participants performed the following tests: 1) a maximal cycling incremental test to measure the ventilatory threshold and maximal oxygen uptake (V̇O2max); 2) a cycling workload constant test at moderate domain (90% ventilatory threshold); 3) a cycling workload constant test at severe domain (110% V̇O2max). Oxygen uptake and plasma lactate were measured during the tests. The contributions of the aerobic (AMET), anaerobic lactic (LAMET), and anaerobic alactic (ALMET) systems were calculated based on the oxygen uptake during exercise, the oxygen energy equivalents provided by lactate accumulation, and the fast component of excess post-exercise oxygen consumption, respectively. In order to assess the intra-investigator variation, four different investigators performed the analyses independently using GEDAE-LaB. A direct comparison with commercial software was also provided. All subjects completed 10 min of exercise at moderate domain, while the time to exhaustion at severe domain was 144 ± 65 s. The AMET, LAMET, and ALMET contributions during moderate domain were about 93, 2, and 5%, respectively. The AMET, LAMET, and ALMET contributions during severe domain were about 66, 21, and 13%, respectively. No statistical differences were found between the energy system contributions and energy expenditure obtained by GEDAE-LaB and commercial software for both moderate and severe domains (P > 0.05). The ICC revealed that these estimates were highly reliable among the four investigators for both moderate and severe domains (all ICC ≥ 0.94). These findings suggest that GEDAE-LaB is a free software easily comprehended by users minimally familiarized with adopted procedures for calculations of energetic profile using oxygen uptake and lactate accumulation during exercise. By providing availability of the software and its source code we hope to facilitate future related research.

Human Physiological Responses to Cycle Ergometer Leg Exercise During +Gz Acceleration

NASA Technical Reports Server (NTRS)

Chou, J. L.; Stad, N. J.; Barnes, P. R.; Leftheriotis, G. P. N.; Arndt, N. F.; Simonson, S.; Greenleaf, J. E.

1998-01-01

Spaceflight and bed-rest deconditioning decrease maximal oxygen uptake (aerobic power), strength, endurance capacity, and orthostatic tolerance. In addition to extensive use of muscular exercise conditioning as a countermeasure for the reduction in aerobic power (VO(sub 2max)), stimuli from some form of +Gz acceleration conditioning may be necessary to attenuate the orthostatic intolerance component of this deconditioning. Hypothesis: There will be no significant difference in the physiological responses (oxygen uptake, heart rate, ventilation, or respiratory exchange ratio) during supine exercise with moderate +Gz acceleration.

Fermentation process using specific oxygen uptake rates as a process control

DOEpatents

Van Hoek, Pim; Aristidou, Aristos; Rush, Brian J.

2016-08-30

Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.

Fermentation process using specific oxygen uptake rates as a process control

DOEpatents

Van Hoek, Pim [Minnetonka, MN; Aristidou, Aristos [Maple Grove, MN; Rush, Brian [Minneapolis, MN

2011-05-10

Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.

Fermentation process using specific oxygen uptake rates as a process control

DOEpatents

Hoek, Van; Pim, Aristidou [Minnetonka, MN; Aristos, Rush [Maple Grove, MN; Brian, [Minneapolis, MN

2007-06-19

Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.

Fermentation process using specific oxygen uptake rates as a process control

DOEpatents

Van Hoek, Pim; Aristidou, Aristos; Rush, Brian

2014-09-09

Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.

Effects of Ultraviolet Radiation on the Oxygen Uptake Rate of the Rabbit Cornea

DTIC Science & Technology

1989-07-01

typical of a noncoherent source Optometrist, Ph.D. exposure. IV Effects on Corneal Oxygen Uptake-Lattimore 117 AvxAtl,-blity Codes 1- -il and/or , "t i...romator entrance slit by the housing optics . A 10 reciprocity (i.e., the biologic effects or endpoints cm quartz-enclosed water chamber was placed be...remove the infrared radiation. The exit optical taneous output at 350.7 and 356.4 nm (3:1 ratio), beam was focused by a quartz lens with a beam size

Oceanic Uptake of Oxygen During Deep Convection Events Through Diffusive and Bubble-Mediated Gas Exchange

NASA Astrophysics Data System (ADS)

Sun, Daoxun; Ito, Takamitsu; Bracco, Annalisa

2017-10-01

The concentration of dissolved oxygen (O2) plays fundamental roles in diverse chemical and biological processes throughout the oceans. The balance between the physical supply and the biological consumption controls the O2 level of the interior ocean, and the O2 supply to the deep waters can only occur through deep convection in the polar oceans. We develop a theoretical framework describing the oceanic O2 uptake during open-ocean deep convection events and test it against a suite of numerical sensitivity experiments. Our framework allows for two predictions, confirmed by the numerical simulations. First, both the duration and the intensity of the wintertime cooling contribute to the total O2 uptake for a given buoyancy loss. Stronger cooling leads to deeper convection and the oxygenation can reach down to deeper depths. Longer duration of the cooling period increases the total amount of O2 uptake over the convective season. Second, the bubble-mediated influx of O2 tends to weaken the diffusive influx by shifting the air-sea disequilibrium of O2 toward supersaturation. The degree of compensation between the diffusive and bubble-mediated gas exchange depends on the dimensionless number measuring the relative strength of oceanic vertical mixing and the gas transfer velocity. Strong convective mixing, which may occur under strong cooling, reduces the degree of compensation so that the two components of gas exchange together drive exceptionally strong oceanic O2 uptake.

A Course in... Biochemical Engineering.

ERIC Educational Resources Information Center

Ng, Terry K-L.; And Others

1988-01-01

Describes a chemical engineering course for senior undergraduates and first year graduate students in biochemical engineering. Discusses five experiments used in the course: aseptic techniques, dissolved oxygen measurement, oxygen uptake by yeast, continuous sterilization, and cultivation of microorganisms. (MVL)

Electrochemistry suggests proton access from the exit site to the binuclear center in Paracoccus denitrificans cytochrome c oxidase pathway variants.

PubMed

Meyer, Thomas; Melin, Frédéric; Richter, Oliver-M H; Ludwig, Bernd; Kannt, Aimo; Müller, Hanne; Michel, Hartmut; Hellwig, Petra

2015-02-27

Two different pathways through which protons access cytochrome c oxidase operate during oxygen reduction from the mitochondrial matrix, or the bacterial cytoplasm. Here, we use electrocatalytic current measurements to follow oxygen reduction coupled to proton uptake in cytochrome c oxidase isolated from Paracoccus denitrificans. Wild type enzyme and site-specific variants with defects in both proton uptake pathways (K354M, D124N and K354M/D124N) were immobilized on gold nanoparticles, and oxygen reduction was probed electrochemically in the presence of varying concentrations of Zn(2+) ions, which are known to inhibit both the entry and the exit proton pathways in the enzyme. Our data suggest that under these conditions substrate protons gain access to the oxygen reduction site via the exit pathway. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Morphological and physiological studies on Indian national kabaddi players.

PubMed Central

Dey, S K; Khanna, G L; Batra, M

1993-01-01

Twenty-five national kabaddi players (Asiad gold medalists 1990), mean age 27.91 years, who attended a national camp at the Sports Authority of India, Bangalore before the Beijing Asian Games in 1990, were investigated for their physical characteristics, body fat, lean body mass (LBM) and somatotype. The physiological characteristics assessed included back strength, maximum oxygen uptake capacity and anaerobic capacity (oxygen debt) and related cardiorespiratory parameters (oxygen pulse, breathing equivalent, maximum pulmonary ventilation, maximum heart rate). Body fat was calculated from skinfold thicknesses taken at four different sites, using Harpenden skinfold calipers. An exercise test (graded protocol) was performed on a bicycle ergometer (ER-900) using a computerized EOS Sprint (Jaeger, West Germany). The mean(s.d.) percentage body fat (17.56(3.48)) of kabaddi players was found to be higher than normal sedentary people. Their physique was found to be endomorphic mesomorph (3.8-5.2-1.7). Mean(s.d.) back strength, maximum oxygen uptake capacity (VO2max) and oxygen debt were found to be 162.6(18.08) kg, 42.6(4.91) ml kg-1 min-1 and 5.02(1.29) litre respectively. Physical characteristics, percentage body fat, somatotype, maximum oxygen uptake capacity and anaerobic capacity (oxygen debt) and other cardiorespiratory parameters were compared with other national counterparts. Present data are comparable with data for judo, wrestling and weightlifting. Since no such study has been conducted on international counterparts, these data could not be compared. These data may act as a guideline in the selection of future kabaddi players and to attain the physiological status comparable to the present gold medalists. Images Figure 4 Figure 5 p242-a PMID:8130960

Using Argo-O2 data to examine the impact of deep-water formation events on oxygen uptake in the Labrador Sea

NASA Astrophysics Data System (ADS)

Wolf, M. K.; Hamme, R. C.; Gilbert, D.; Yashayaev, I.

2016-02-01

Deep-water formation allows the deep ocean to communicate with the atmosphere, facilitating exchanges of heat as well as important gases such as CO2 and oxygen. The Labrador Sea is the most studied location of deep convection in the North Atlantic Ocean and a strong contributor to the global thermohaline circulation. Since there are no internal sources of oxygen below the euphotic zone, deep-water formation is vital for oxygen transport to the deep ocean. Recent studies document large interannual variability in the strength and depth of convection in the Labrador Sea, from mixed layers of 100m to greater than 1000m. A weakening of this deep convection starves the deep ocean of oxygen, disrupting crucial deep sea biological processes, as well as reducing oceanic CO2 uptake and ocean circulation. We used data from the extensive Argo float network to examine these deep-water formation events in the Labrador Sea. The oxygen optodes onboard many Argo floats suffer from biases whose amplitude must be determined; therefore we investigated and applied various optode calibration methods. Using calibrated vertical profiles of oxygen, temperature, and salinity, we observed the timing, magnitude, and location of deep convection, restratification, and spring phytoplankton blooms. In addition, we used surface oxygen values along with NCEP wind speeds to calculate the air-sea oxygen flux using a range of air-sea gas exchange parameterizations. We then compared this oxygen flux to the rate of change of the measured oxygen inventory. Where the inventory and flux did not agree, we identified other oceanic processes such as biological activity or lateral advection of water masses occurring, or advection of the float itself into a new area. The large role that horizontal advection of water or the float has on oxygen uptake and cycling leads us to conclude that this data cannot be easily interpreted as a 1-D system. Oxygen exchanges with the atmosphere at a faster rate than CO2, is more affected by bubble injection, and reacts differently to temperature change. Oxygen is also produced and consumed by photosynthesis and respiration respectively at a specific ratio to CO2. These properties enable us to use oxygen as a separate constraint from carbon to determine the effect these various processes have on gas cycling, and the global ocean circulation.

ESCA Study of Poly (Vinylidene Fluoride) Tetrafluoroethylene - Ethylene Copolymer and Polyethylene Exposed to Atomic Oxygen

NASA Technical Reports Server (NTRS)

Golub, Morton A.; Cormia, Robert D.

1989-01-01

The ESCA (electron spectroscopy for chemical analysis) spectra of films of poly(vinylidene fluoride) (PVDF), tetrafluoroethylene-ethylene copolymer (TFE/ET) and polyethylene (PE) exposed to atomic oxygen (O(P-3)), in or out of the glow of a radio-frequency O2 plasma, were compared. ESCA spectra of PE films exposed to (O(P-3)) in low Earth orbit (LEO) on the STS-8 Space Shuttle were also examined. Apart from O(P-3)-induced surface recession (etching), the various polymer films exhibited surface oxidation, which proceeded towards equilibrium saturation oxygen levels. The maximum surface oxygen uptakes for in-glow or out-of-glow exposures were in the order: PE greater than TFE/ET greater than PVDF; for PE itself, the oxygen uptakes were in the order: in glow greater than out of glow greater than LEO. Given prior ESCA data on poly(vinyl fluoride) and polytetrafluoroethylene films exposed to O(P-3), the extent of surface oxidation is seen to decrease regularly with increase in fluorine substitution in a family of ethylene-type polymers. (Keywords: ESCA; poly(vinylidene fluoride); tetrafluoroethylene ethylene copolymer; polyethylene; atomic oxygen; radio-frequency oxygen plasma; low Earth orbit)

Linear and non-linear contributions to oxygen transport and utilization during moderate random exercise in humans.

PubMed

Beltrame, T; Hughson, R L

2017-05-01

What is the central question of this study? The pulmonary oxygen uptake (pV̇O2) data used to study the muscle aerobic system dynamics during moderate-exercise transitions is classically described as a mono-exponential function controlled by a complex interaction of the oxygen delivery-utilization balance. This elevated complexity complicates the acquisition of relevant information regarding aerobic system dynamics based on pV̇O2 data during a varying exercise stimulus. What is the main finding and its importance? The elevated complexity of pV̇O2 dynamics is a consequence of a multiple-order interaction between muscle oxygen uptake and circulatory distortion. Our findings challenge the use of a first-order function to study the influences of the oxygen delivery-utilization balance over the pV̇O2 dynamics. The assumption of aerobic system linearity implies that the pulmonary oxygen uptake (pV̇O2) dynamics during exercise transitions present a first-order characteristic. The main objective of this study was to test the linearity of the oxygen delivery-utilization balance during random moderate exercise. The cardiac output (Q̇) and deoxygenated haemoglobin concentration ([HHb]) were measured to infer the central and local O 2 availability, respectively. Thirteen healthy men performed two consecutive pseudorandom binary sequence cycling exercises followed by an incremental protocol. The system input and the outputs pV̇O2, [HHb] and Q̇ were submitted to frequency-domain analysis. The linearity of the variables was tested by computing the ability of the response at a specific frequency to predict the response at another frequency. The predictability levels were assessed by the coefficient of determination. In a first-order system, a participant who presents faster dynamics at a specific frequency should also present faster dynamics at any other frequency. All experimentally obtained variables (pV̇O2, [HHb] and Q̇) presented a certainly degree of non-linearity. The local O 2 availability, evaluated by the ratio pV̇O2/[HHb], presented the most irregular behaviour. The overall [HHb] kinetics were faster than pV̇O2 and Q̇ kinetics. In conclusion, the oxygen delivery-utilization balance behaved as a non-linear phenomenon. Therefore, the elevated complexity of the pulmonary oxygen uptake dynamics is governed by a complex multiple-order interaction between the oxygen delivery and utilization systems. © 2017 The Authors. Experimental Physiology © 2017 The Physiological Society.

Influence of low oxygen tensions and sorption to sediment black carbon on biodegradation of pyrene.

PubMed

Ortega-Calvo, José-Julio; Gschwend, Philip M

2010-07-01

Sorption to sediment black carbon (BC) may limit the aerobic biodegradation of polycyclic aromatic hydrocarbons (PAHs) in resuspension events and intact sediment beds. We examined this hypothesis experimentally under conditions that were realistic in terms of oxygen concentrations and BC content. A new method, based on synchronous fluorescence observations of (14)C-pyrene, was developed for continuously measuring the uptake of dissolved pyrene by Mycobacterium gilvum VM552, a representative degrader of PAHs. The effect of oxygen and pyrene concentrations on pyrene uptake followed Michaelis-Menten kinetics, resulting in a dissolved oxygen half-saturation constant (K(om)) of 14.1 microM and a dissolved pyrene half-saturation constant (K(pm)) of 6 nM. The fluorescence of (14)C-pyrene in air-saturated suspensions of sediments and induced cells followed time courses that reflected simultaneous desorption and biodegradation of pyrene, ultimately causing a quasi-steady-state concentration of dissolved pyrene balancing desorptive inputs and biodegradation removals. The increasing concentrations of (14)CO(2) in these suspensions, as determined with liquid scintillation, evidenced the strong impact of sorption to BC-rich sediments on the biodegradation rate. Using the best-fit parameter values, we integrated oxygen and sorption effects and showed that oxygen tensions far below saturation levels in water are sufficient to enable significant decreases in the steady-state concentrations of aqueous-phase pyrene. These findings may be relevant for bioaccumulation scenarios that consider the effect of sediment resuspension events on exposure to water column and sediment pore water, as well as the direct uptake of PAHs from sediments.

Low oxygen tension enhances endothelial fate of human pluripotent stem cells.

PubMed

Kusuma, Sravanti; Peijnenburg, Elizabeth; Patel, Parth; Gerecht, Sharon

2014-04-01

A critical regulator of the developing or regenerating vasculature is low oxygen tension. Precise elucidation of the role of low oxygen environments on endothelial commitment from human pluripotent stem cells necessitates controlled in vitro differentiation environments. We used a feeder-free, 2-dimensional differentiation system in which we could monitor accurately dissolved oxygen levels during human pluripotent stem cell differentiation toward early vascular cells (EVCs). We found that oxygen uptake rate of differentiating human pluripotent stem cells is lower in 5% O2 compared with atmospheric conditions. EVCs differentiated in 5% O2 had an increased vascular endothelial cadherin expression with clusters of vascular endothelial cadherin+ cells surrounded by platelet-derived growth factor β+ cells. When we assessed the temporal effects of low oxygen differentiation environments, we determined that low oxygen environments during the early stages of EVC differentiation enhance endothelial lineage commitment. EVCs differentiated in 5% O2 exhibited an increased expression of vascular endothelial cadherin and CD31 along with their localization to the membrane, enhanced lectin binding and acetylated low-density lipoprotein uptake, rapid cord-like structure formation, and increased expression of arterial endothelial cell markers. Inhibition of reactive oxygen species generation during the early stages of differentiation abrogated the endothelial inductive effects of the low oxygen environments. Low oxygen tension during early stages of EVC derivation induces endothelial commitment and maturation through the accumulation of reactive oxygen species, highlighting the importance of regulating oxygen tensions during human pluripotent stem cell-vascular differentiation.

Identification of an iron permease, cFTR1, in cyanobacteria involved in the iron reduction/re-oxidation uptake pathway.

PubMed

Xu, Ning; Qiu, Guo-Wei; Lou, Wen-Jing; Li, Zheng-Ke; Jiang, Hai-Bo; Price, Neil M; Qiu, Bao-Sheng

2016-12-01

Cyanobacteria are globally important primary producers and abundant in many iron-limited aquatic environments. The ways in which they take up iron are largely unknown, but reduction of Fe 3+ is an important step in the process. Here we report a special iron permease in Synechocystis, cFTR1, that is required for Fe 3+ uptake following Fe 2+ re-oxidation. The expression of cFTR1 is induced by iron starvation, and a mutant lacking the gene is abnormally sensitive to iron starvation. The cFTR1 protein localizes to the plasma membrane and contains the iron-binding motif "REXXE". Point-directed mutagenesis of the REXXE motif results in a sensitivity to Fe-deficiency. Measurements of iron ( 55 Fe) uptake rate show that cFTR1 takes up Fe 3+ rather than Fe 2+ . The function of cFTR1 in Synechocystis could be genetically complemented by the iron permease, Ftr1p, of Saccharomyces cerevisiae, that is known to transport Fe 3+ produced by the oxidation of Fe 2+ via a multicopper oxidase. Unlike yeast Ftr1p, cyanobacterial cFTR1 probably obtains Fe 3+ primarily from the oxidation of Fe 2+ by oxygen. Growth assays show that the cFTR1 is required during oxygenic, photoautotrophic growth but not when oxygen production is inhibited during photoheterotrophic growth. In cyanobacteria, iron reduction/re-oxidation uptake pathway may represent their adaptation to oxygenated environments. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

Age-related changes in oxygen and nutrient uptake by hindquarters in newborn pigs during cold-induced shivering.

PubMed

Lossec, G; Lebreton, Y; Hulin, J C; Fillaut, M; Herpin, P

1998-11-01

Newborn pigs rely essentially on shivering thermogenesis in the cold. In order to understand the rapid postnatal enhancement of thermogenic capacities in piglets, the oxygen and nutrient uptake of hindquarters was measured in vivo in 1- (n = 6) and 5-day-old (n = 6) animals at thermal neutrality and during cold exposure. The hindquarters were considered to represent a skeletal muscle compartment. Indirect calorimetry and arterio-venous techniques were used. The cold challenge (23 C at 1 day old and 15 C at 5 days old for 90 min) induced a similar increase (+90 %) in regulatory heat production at both ages. Hindquarters blood flow was higher at 5 days than 1 day old at thermal neutrality (26 +/- 3 vs. 17 +/- 1 ml min-1 (100 g hindquarters)-1) and its increase in the cold was much more marked (+65 % at 5 days old vs. +25 % at 1 day old). Oxygen extraction by the hindquarters rose from 30-35 % at thermal neutrality to 65-70 % in the cold at both ages. The calculated contribution of skeletal muscle to total oxygen consumption averaged 34-40 % at thermal neutrality and 50-64 % in the cold and skeletal muscle was the major contributor to regulatory thermogenesis. Based on hindquarters glucose uptake and lactate release, carbohydrate appeared to be an important fuel for shivering. However, net uptake of fatty acids increased progressively during cold exposure at 5 days old. The enhancement in muscular blood supply and fatty acid utilization during shivering is probably related to the postnatal improvement in the thermoregulatory response of the piglet.

Simultaneous phosphorus uptake and denitrification by EBPR-r biofilm under aerobic conditions: effect of dissolved oxygen.

PubMed

Wong, Pan Yu; Ginige, Maneesha P; Kaksonen, Anna H; Cord-Ruwisch, Ralf; Sutton, David C; Cheng, Ka Yu

2015-01-01

A biofilm process, termed enhanced biological phosphorus removal and recovery (EBPR-r), was recently developed as a post-denitrification approach to facilitate phosphorus (P) recovery from wastewater. Although simultaneous P uptake and denitrification was achieved despite substantial intrusion of dissolved oxygen (DO >6 mg/L), to what extent DO affects the process was unclear. Hence, in this study a series of batch experiments was conducted to assess the activity of the biofilm under various DO concentrations. The biofilm was first allowed to store acetate (as internal storage) under anaerobic conditions, and was then subjected to various conditions for P uptake (DO: 0-8 mg/L; nitrate: 10 mg-N/L; phosphate: 8 mg-P/L). The results suggest that even at a saturating DO concentration (8 mg/L), the biofilm could take up P and denitrify efficiently (0.70 mmol e(-)/g total solids*h). However, such aerobic denitrification activity was reduced when the biofilm structure was physically disturbed, suggesting that this phenomenon was a consequence of the presence of oxygen gradient across the biofilm. We conclude that when a biofilm system is used, EBPR-r can be effectively operated as a post-denitrification process, even when oxygen intrusion occurs.

An in silico analysis of oxygen uptake of a mild COPD patient during rest and exercise using a portable oxygen concentrator

PubMed Central

Katz, Ira; Pichelin, Marine; Montesantos, Spyridon; Kang, Min-Yeong; Sapoval, Bernard; Zhu, Kaixian; Thevenin, Charles-Philippe; McCoy, Robert; Martin, Andrew R; Caillibotte, Georges

2016-01-01

Oxygen treatment based on intermittent-flow devices with pulse delivery modes available from portable oxygen concentrators (POCs) depends on the characteristics of the delivered pulse such as volume, pulse width (the time of the pulse to be delivered), and pulse delay (the time for the pulse to be initiated from the start of inhalation) as well as a patient’s breathing characteristics, disease state, and respiratory morphology. This article presents a physiological-based analysis of the performance, in terms of blood oxygenation, of a commercial POC at different settings using an in silico model of a COPD patient at rest and during exercise. The analysis encompasses experimental measurements of pulse volume, width, and time delay of the POC at three different settings and two breathing rates related to rest and exercise. These experimental data of device performance are inputs to a physiological-based model of oxygen uptake that takes into account the real dynamic nature of gas exchange to illustrate how device- and patient-specific factors can affect patient oxygenation. This type of physiological analysis that considers the true effectiveness of oxygen transfer to the blood, as opposed to delivery to the nose (or mouth), can be instructive in applying therapies and designing new devices. PMID:27729783

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.

Nanocrystalline diamond protects Zr cladding surface against oxygen and hydrogen uptake: Nuclear fuel durability enhancement.

PubMed

Škarohlíd, Jan; Ashcheulov, Petr; Škoda, Radek; Taylor, Andrew; Čtvrtlík, Radim; Tomáštík, Jan; Fendrych, František; Kopeček, Jaromír; Cháb, Vladimír; Cichoň, Stanislav; Sajdl, Petr; Macák, Jan; Xu, Peng; Partezana, Jonna M; Lorinčík, Jan; Prehradná, Jana; Steinbrück, Martin; Kratochvílová, Irena

2017-07-25

In this work, we demonstrate and describe an effective method of protecting zirconium fuel cladding against oxygen and hydrogen uptake at both accident and working temperatures in water-cooled nuclear reactor environments. Zr alloy samples were coated with nanocrystalline diamond (NCD) layers of different thicknesses, grown in a microwave plasma chemical vapor deposition apparatus. In addition to showing that such an NCD layer prevents the Zr alloy from directly interacting with water, we show that carbon released from the NCD film enters the underlying Zr material and changes its properties, such that uptake of oxygen and hydrogen is significantly decreased. After 100-170 days of exposure to hot water at 360 °C, the oxidation of the NCD-coated Zr plates was typically decreased by 40%. Protective NCD layers may prolong the lifetime of nuclear cladding and consequently enhance nuclear fuel burnup. NCD may also serve as a passive element for nuclear safety. NCD-coated ZIRLO claddings have been selected as a candidate for Accident Tolerant Fuel in commercially operated reactors in 2020.

The effects of temperature and salinity on 17-α-ethynylestradiol uptake and its relationship to oxygen consumption in the model euryhaline teleost (Fundulus heteroclitus).

PubMed

Blewett, Tamzin; MacLatchy, Deborah L; Wood, Chris M

2013-02-01

The synthetic estrogen 17-α-ethynylestradiol (EE2), a component of birth control and hormone replacement therapy, is discharged into the environment via wastewater treatment plant (WWTP) effluents. The present study employed radiolabeled EE2 to examine impacts of temperature and salinity on EE2 uptake in male killifish (Fundulus heteroclitus). Fish were exposed to a nominal concentration of 100ng/L EE2 for 2h. The rate of EE2 uptake was constant over the 2h period. Oxygen consumption rates (MO(2)), whole body uptake rates, and tissue-specific EE2 distribution were determined. In killifish acclimated to 18°C at 16ppt (50% sea water), MO(2) and EE2 uptake were both lower after 24h exposure to 10°C and 4°C, and increased after 24h exposure to 26°C. Transfer to fresh water (FW) for 24h lowered EE2 uptake rate, and long-term acclimation to fresh water reduced it by 70%. Both long-term acclimation to 100% sea water (32ppt) and a 24h transfer to 100% sea water also reduced EE2 uptake rate by 50% relative to 16ppt. Tissue-specific accumulation of EE2 was highest (40-60% of the total) in the liver plus gall bladder across all exposures, and the vast majority of this was in the bile at 2h, regardless of temperature or salinity. The carcass was the next highest accumulator (30-40%), followed by the gut (10-20%) with only small amounts in gill and spleen. Killifish chronically exposed (15 days) to 100ng/L EE2 displayed no difference in EE2 uptake rate or tissue-specific distribution. Drinking rate, measured with radiolabeled polyethylene glycol-4000, was about 25 times greater in 16ppt-acclimated killifish relative to FW-acclimated animals. However, drinking accounted for less than 30% of gut accumulation, and therefore a negligible percentage of whole body EE2 uptake rates. In general, there were strong positive relationships between EE2 uptake rates and MO(2), suggesting similar uptake pathways of these lipophilic molecules across the gills. These data will be useful in developing a predictive model of how key environmental parameter variations (salinity, temperature, dissolved oxygen) affect EE2 uptake in estuarine fish, to determine optimal timing and location of WWTP discharges. Copyright © 2012 Elsevier B.V. All rights reserved.

Uptake of Light Elements in Thin Metallic Films

NASA Astrophysics Data System (ADS)

Markwitz, Andreas; Waldschmidt, Mathias

Ion beam analysis was used to investigate the influence of substrate temperature on the inclusion of impurities during the deposition process of thin metallic single and double layers. Thin layers of gold and aluminium were deposited at different temperatures onto thin copper layers evaporated on silicon wafer substrates. The uptake of oxygen in the layers was measured using the highly sensitive non-resonant reaction 16O(d,p)170O at 920 keV. Nuclear reaction analysis was also used to probe for carbon and nitrogen with a limit of detection better than 20 ppm. Hydrogen depth profiles were measured using elastic recoil detection on the nanometer scale. Rutherford backscattering spectroscopy was used to determine the depth profiles of the metallic layers and to study diffusion processes. The combined ion beam analyses revealed an uptake of oxygen in the layers depending on the different metallic cap layers and the deposition temperature. Lowest oxygen values were measured for the Au/Cu layers, whereas the highest amount of oxygen was measured in Al/Cu layers deposited at 300°C. It was also found that with single copper layers produced at various temperatures, oxygen contamination occurred during the evaporation process and not afterwards, for example, as a consequence of the storage of the films under normal conditions for several days. Hydrogen, carbon, and nitrogen were found as impurities in the single and double layered metallic films, a finding that is in agreement with the measured oxidation behaviour of the metallic films.

Skeletal muscle fatigue precedes the slow component of oxygen uptake kinetics during exercise in humans.

PubMed

Cannon, Daniel T; White, Ailish C; Andriano, Melina F; Kolkhorst, Fred W; Rossiter, Harry B

2011-02-01

The mechanisms determining exercise intolerance are poorly understood. A reduction in work efficiency in the form of an additional energy cost and oxygen requirement occurs during high-intensity exercise and contributes to exercise limitation. Muscle fatigue and subsequent recruitment of poorly efficient muscle fibres has been proposed to mediate this decline. These data demonstrate in humans, that muscle fatigue, generated in the initial minutes of exercise, is correlated with the increasing energy demands of high-intensity exercise. Surprisingly, however, while muscle fatigue reached a plateau, oxygen uptake continued to increase throughout 8 min of exercise. This suggests that additional recruitment of inefficient muscle fibres may not be the sole mechanism contributing to the decline in work efficiency during high-intensity exercise.

Functional significance of cardiac reinnervation in heart transplant recipients.

PubMed

Schwaiblmair, M; von Scheidt, W; Uberfuhr, P; Ziegler, S; Schwaiger, M; Reichart, B; Vogelmeier, C

1999-09-01

There is accumulating evidence of structural sympathetic reinnervation after human cardiac transplantation. However, the functional significance of reinnervation in terms of exercise capacity has not been established as yet; we therefore investigated the influence of reinnervation on cardiopulmonary exercise testing. After orthotopic heart transplantation 35 patients (mean age, 49.1 +/- 8.4 years) underwent positron emission tomography with scintigraphically measured uptake of C11-hydroxyephedrine (HED), lung function testing, and cardiopulmonary exercise testing. Two groups were defined based on scintigraphic findings, indicating a denervated group (n = 15) with a HED uptake of 5.45%/min and a reinnervated group (n = 20) with a HED uptake of 10.59%/min. The two study groups did not show significant differences with regard to anthropometric data, number of rejection episodes, preoperative hemodynamics, and postoperative lung function data. The reinnervated group had a significant longer time interval from transplantation (1625 +/- 1069 versus 800 +/- 1316 days, p < .05). In transplant recipients with reinnervation, heart rate at maximum exercise (137 +/- 15 versus 120 +/- 20 beats/min, p = .012), peak oxygen uptake (21.0 +/- 4 versus 16.1 +/- 5 mL/min/kg, p = .006), peak oxygen pulse (12.4 +/- 2.9 versus 10.2 +/- 2.7 mL/min/beat, p = .031), and anaerobic threshold (11.2 +/- 1.8 versus 9.5 +/- 2.1 mL/min, p = .046) were significantly increased in comparison to denervated transplant recipients. Additionally, a decreased functional dead space ventilation (0.24 +/- 0.05 versus 0.30 +/- 0.05, p = .004) was observed in the reinnervated group. Our study results support the hypothesis that partial sympathetic reinnervation after cardiac transplantation is of functional significance. Sympathetic reinnervation enables an increased peak oxygen uptake. This is most probably due to partial restoration of the chronotropic and inotropic competence of the heart as well as an improved oxygen delivery to the exercising muscles and a reduced ventilation-perfusion mismatching.

Laser irradiation of mouse spermatozoa enhances in-vitro fertilization and Ca2+ uptake via reactive oxygen species

NASA Astrophysics Data System (ADS)

Cohen, Natalie; Lubart, Rachel; Rubinstein, Sara; Breitbart, Haim

1996-11-01

630 nm He-Ne laser irradiation was found to have a profound influence on Ca2+ uptake in mouse spermatozoa and the fertilizing potential of these cells. Laser irradiation affected mainly the mitochondrial Ca2+ transport mechanisms. Furthermore, the effect of light was found to be Ca2+-dependent. We demonstrate that reactive oxygen species (ROS) are involved in the cascade of biochemical events evoked by laser irradiation. A causal association between laser irradiation, ROS generation, and sperm function was indicated by studies with ROS scavengers, superoxide dismutase (SOD) and catalase, and exogenous hydrogen peroxide. SOD treatment resulted in increased Ca2+ uptake and in enhanced fertilization rate. Catalase treatment impaired the light-induced stimulation in Ca2+ uptake and fertilization rate. Exogenous hydrogen peroxide was found to enhance Ca2+ uptake in mouse spermatozoa and the fertilizing capability of these cells in a dose-dependent manner. These results suggest that the effect of 630 nm He-Ne laser irradiation is mediated through the generation of hydrogen peroxide by the spermatozoa and that this effect plays a significant role in the augmentation of the sperm cells' capability to fertilize metaphase II-arrested eggs in-vitro.

Excess Iodide Induces an Acute Inhibition of the Sodium/Iodide Symporter in Thyroid Male Rat Cells by Increasing Reactive Oxygen Species

PubMed Central

Arriagada, Alejandro A.; Albornoz, Eduardo; Opazo, Ma. Cecilia; Becerra, Alvaro; Vidal, Gonzalo; Fardella, Carlos; Michea, Luis; Carrasco, Nancy; Simon, Felipe; Elorza, Alvaro A.; Bueno, Susan M.; Kalergis, Alexis M.

2015-01-01

Na+/I− symporter (NIS) mediates iodide (I−) uptake in the thyroid gland, the first and rate-limiting step in the biosynthesis of the thyroid hormones. The expression and function of NIS in thyroid cells is mainly regulated by TSH and by the intracellular concentration of I−. High doses of I− for 1 or 2 days inhibit the synthesis of thyroid hormones, a process known as the Wolff-Chaikoff effect. The cellular mechanisms responsible for this physiological response are mediated in part by the inhibition of I− uptake through a reduction of NIS expression. Here we show that inhibition of I− uptake occurs as early as 2 hours or 5 hours after exposure to excess I− in FRTL-5 cells and the rat thyroid gland, respectively. Inhibition of I− uptake was not due to reduced NIS expression or altered localization in thyroid cells. We observed that incubation of FRTL-5 cells with excess I− for 2 hours increased H2O2 generation. Furthermore, the inhibitory effect of excess I− on NIS-mediated I− transport could be recapitulated by H2O2 and reverted by reactive derived oxygen species scavengers. The data shown here support the notion that excess I− inhibits NIS at the cell surface at early times by means of a posttranslational mechanism that involves reactive derived oxygen species. PMID:25594695

Mineralisation assays of some organic resources of aquatic systems.

PubMed

Bitar, A L; Bianchini, Júnior I

2002-11-01

Assays were carried out to evaluate the consumption of dissolved oxygen resulting from mineralisation processes in resources usually found in aquatic systems. They were also aimed at estimating the oxygen uptake rate of each investigated process. Experiments were conducted using substrates from 3 different places. A fixed amount of substrate was added to 5 litres of water from Lagoa do Infernão that was previously filtered with glass wool. After adding the substrates the bottles were aired and the amount of dissolved oxygen and the temperature were monitored for 55 days. The occurrence of anaerobic processes was avoided by reoxygenating the bottles. The experimental results were fitted to a first order kinetics model, from which the consumption of dissolved oxygen owing to mineralisation processes was obtained. The amount of oxygen uptake from the mineralisation processes appeared in the following decreasing order: Wolffia sp., Cabomba sp., Lemna sp., DOM (Dissolved Organic Matter), Salvinia sp., Scirpus cubensis, stem, Eichhornia azurea, sediment and humic compounds. The deoxygenation rates (day-1) were: 0.267 (humic compounds), 0.230 (Lemna sp.), 0.199 (E. azurea), 0.166 (S. cubensis), 0.132 (sediment), 0.126 (DOM), 0.093 (Cabomba sp.), 0.091 (stem), 0.079 (Salvinia sp. and Wolffia sp.). From these results, 2 groups of resources could be identified: the first one consists of detritus with higher amounts of labile (ready to use) compounds, which show a higher global oxygen uptake during the mineralisation process; the second one consists mainly of resources that show refracting characteristics. However, when the consumption rates are analysed it is noted that the mineralised parts of the refracting substrates can be easier to process than the labile fractions of the less refracting resources.

Sevoflurane protects rat mixed cerebrocortical neuronal-glial cell cultures against transient oxygen-glucose deprivation: involvement of glutamate uptake and reactive oxygen species.

PubMed

Canas, Paula T; Velly, Lionel J; Labrande, Christelle N; Guillet, Benjamin A; Sautou-Miranda, Valérie; Masmejean, Frédérique M; Nieoullon, André L; Gouin, François M; Bruder, Nicolas J; Pisano, Pascale S

2006-11-01

The purpose of this study was to clarify the role of glutamate and reactive oxygen species in sevoflurane-mediated neuroprotection on an in vitro model of ischemia-reoxygenation. Mature mixed cerebrocortical neuronal-glial cell cultures, treated or not with increasing concentrations of sevoflurane, were exposed to 90 min combined oxygen-glucose deprivation (OGD) in an anaerobic chamber followed by reoxygenation. Cell death was quantified by lactate dehydrogenase release into the media and cell viability by reduction of 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium by mitochondrial succinate dehydrogenase. Extracellular concentrations of glutamate and glutamate uptake were assessed at the end of the ischemic injury by high-performance liquid chromatography and incorporation of L-[H]glutamate into cells, respectively. Free radical generation in cells was assessed 6 h after OGD during the reoxygenation period using 2',7'-dichlorofluorescin diacetate, which reacts with intracellular radicals to be converted to its fluorescent product, 2',7'-dichlorofluorescin, in cell cytosol. Twenty-four hours after OGD, sevoflurane, in a concentration-dependent manner, significantly reduced lactate dehydrogenase release and increased cell viability. At the end of OGD, sevoflurane was able to reduce the OGD-induced decrease in glutamate uptake. This effect was impaired in the presence of threo-3-methyl glutamate, a specific inhibitor of the glial transporter GLT1. Sevoflurane counteracted the increase in extracellular level of glutamate during OGD and the generation of reactive oxygen species during reoxygenation. Sevoflurane had a neuroprotective effect in this in vitro model of ischemia-reoxygenation. This beneficial effect may be explained, at least in part, by sevoflurane-induced antiexcitotoxic properties during OGD, probably depending on GLT1, and by sevoflurane-induced decrease of reactive oxygen species generation during reoxygenation.

[TRANSPORT OF OXYGEN DURING GEOMETRICAL RECONSTRUCTION OF THE LEFT VENTRICLE IN CONJUNCTION WITH CORONARY ARTERY BYPASS GRAFTING AND USING OF HIGH THORACIC EPIDURAL ANESTHESIA AS A MAJOR COMPONENT OF GENERAL ANAESTHESIA].

PubMed

Zatevahina, M V; Farzutdinov, A F; Rahimov, A A; Makrushin, I M; Kvachantiradze, G Y

2015-01-01

The purpose of the study is to examine the perioperative dynamics of strategic blood oxygen transport indicators: delivery (DO2), consumption (VO2), the coefficient of oxygen uptake (CUO2) and their composition, as well as the dynamics of blood lactate indicators in patients with ischaemic heart disease (IHD) who underwent surgery under cardiopulmonary bypass with high thoracic epidural anaesthesia (HTEA) as the main component of anesthesia. Research was conducted in 30 patients with a critical degree of operational risk, during the correction of post-infarction heart aneurysmn using the V. Dor method in combination with coronary artery bypass grafting. The strategic blood oxygen transport indicators (delivery, consumption and the oxygen uptake coefficient) showed a statistically significant decrease compared to the physiological norm and to the initial data at two points of the research: the intubation of the trachea and during cardiopulmonary bypass. The system components of oxygen were influenced at problematic stages by the dynamics of SvO2 (increase), AVD (decrease), hemodilution withe fall of the HIb- in the process of JR in the persence of superficial hypothermia. The maintenance of optimal CA in the context of HTEA, combined with a balanced volemic load and a minimized cardiotonic support ensured the stabilisation of strategic blood oxygen transport indicators aithe postperfusion stage and during the immediate postoperative period The article is dedicated to the study of strategic blood oxygen transport indicators and their components during the operation of geometric reconstruc-tion of the left ventricle combined with coronary artery-bypass using cardiopulmonary bypass and with high thoracic epidural anesthesia as the main component of general anaesthesia. The analysis has covered the stagewise delivery dynamics, consumption and the oxygen uptake coefficient at II stages of the operation and of the immediate postoperative period. The study has ident (fled the causes qf reduced oxygen transport during the preperfu- sion and postperfusion periods, under IR and during the immediate postoperative period. Values of CA, SvO2, AVD, Hb, hemnodilution, T qf the body in oxygen transport indicator dynamics have been proven. A way of maintaining oxygen transport indicators close to the physiological norm in the immediate postoperative period has been justified.

Relationship between volition, physical activity and weight loss maintenance: Study rationale, design, methods and baseline characteristics.

PubMed

Dandanell, Sune; Elbe, Anne-Marie; Pfister, Gertrud; Elsborg, Peter; W Helge, Jørn

2017-05-01

To investigate the relationship between volition, physical activity and weight loss maintenance. We recruited 84 sedentary (maximal oxygen uptake: 25 ± 5 ml/min), overweight and obese (Body mass index (BMI) 38 ± 7 m/h 2 , fat 44 ± 7 %) women ( n = 55) and men ( n = 29) for an interdisciplinary prospective study with follow-up. The change in lifestyle and weight loss is promoted via a 3-month intensive lifestyle intervention at a private health school. The intervention consists of supervised training (1-3 hours/day), a healthy hypo-caloric diet (-500 to -700 kCal/day) and education in healthy lifestyle in classes/groups. The participants' body weight and composition (Dual Energy X-ray absorptiometry), volitional skills (questionnaire), physical activity level (heart rate accelerometer/questionnaire) and maximal oxygen uptake (indirect calorimetry) are to be monitored before, after, and 3 and 12 months after the intervention. At the 12-month follow-up, three different groups will be established: Clinical weight loss maintenance (> 10% weight loss from baseline), moderate weight loss maintenance (1-10% weight loss) and no weight loss (or weight regain). A linear mixed model analysis will be used to compare levels of volitional skills, physical activity and maximal oxygen uptake over time, between the three groups. Correlational analyses will be used to investigate possible associations between volition, maximal oxygen uptake, physical activity level and weight loss maintenance. If specific volitional skills are identified as predictors of adherence to physical activity and success in clinical weight loss maintenance, these can be trained in future intensive lifestyle interventions in order to optimize the success rate.

Noninvasive Screening for Pulmonary Hypertension by Exercise Testing in Congenital Heart Disease.

PubMed

Müller, Jan; Heck, Pinar Bambul; Ewert, Peter; Hager, Alfred

2017-05-01

Patients with congenital heart disease and native or palliated conditions are at risk to develop pulmonary hypertension (PH) in later life. Screening for PH is currently performed by regular echocardiographic follow-up, which appears to be difficult in several congenital conditions. This study evaluated the screening for PH in congenital heart disease by cardiopulmonary exercise testing (CPET). We analyzed our database including all patients with congenital heart disease referred for CPET in our institution from June 2001 to September 2013 and identified 683 patients who had an accompanied heart catheterization less than 6 month after CPET. Those 130 patients with proven PH were compared with the other 563 patients with congenital heart disease but without PH. Peak oxygen uptake was the most discriminative variable, showing two thresholds at 16.3 mL/min per kg and 25.2 mL/min per kg. The highest specificity of 95% for PH was found in patients with a peak oxygen uptake of 16.3 mL/min per kg or less and a breathing reserve of 37.4% or less. In patients with a peak oxygen uptake exceeding 16.3 mL/min per kg, there was a high specificity of 86.3% but a low sensitivity of 53.1%. With 25.2 mL/min per kg as the threshold, the sensitivity for PH was only 10.0%. Detection of PH in patients with congenital heart disease by CPET is difficult because of many falsely positive tests. However, a peak oxygen uptake higher than 25.2 mL/min per kg makes the diagnosis of PH unlikely. Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Alcohol consumption and cardiorespiratory fitness in five population-based studies.

PubMed

Baumeister, Sebastian E; Finger, Jonas D; Gläser, Sven; Dörr, Marcus; Markus, Marcello Rp; Ewert, Ralf; Felix, Stephan B; Grabe, Hans-Jörgen; Bahls, Martin; Mensink, Gert Bm; Völzke, Henry; Piontek, Katharina; Leitzmann, Michael F

2018-01-01

Background Poor cardiorespiratory fitness is a risk factor for cardiovascular morbidity. Alcohol consumption contributes substantially to the burden of disease, but its association with cardiorespiratory fitness is not well described. We examined associations between average alcohol consumption, heavy episodic drinking and cardiorespiratory fitness. Design The design of this study was as a cross-sectional population-based random sample. Methods We analysed data from five independent population-based studies (Study of Health in Pomerania (2008-2012); German Health Interview and Examination Survey (2008-2011); US National Health and Nutrition Examination Survey (NHANES) 1999-2000; NHANES 2001-2002; NHANES 2003-2004) including 7358 men and women aged 20-85 years, free of lung disease or asthma. Cardiorespiratory fitness, quantified by peak oxygen uptake, was assessed using exercise testing. Information regarding average alcohol consumption (ethanol in grams per day (g/d)) and heavy episodic drinking (5+ or 6+ drinks/occasion) was obtained from self-reports. Fractional polynomial regression models were used to determine the best-fitting dose-response relationship. Results Average alcohol consumption displayed an inverted U-type relation with peak oxygen uptake ( p-value<0.0001), after adjustment for age, sex, education, smoking and physical activity. Compared to individuals consuming 10 g/d (moderate consumption), current abstainers and individuals consuming 50 and 60 g/d had significantly lower peak oxygen uptake values (ml/kg/min) (β coefficients = -1.90, β = -0.06, β = -0.31, respectively). Heavy episodic drinking was not associated with peak oxygen uptake. Conclusions Across multiple adult population-based samples, moderate drinkers displayed better fitness than current abstainers and individuals with higher average alcohol consumption.

Preliminary Evidence for Adipocytokine Signals in Skeletal Muscle Glucose Uptake.

PubMed

Kudoh, Akihiro; Satoh, Hiroaki; Hirai, Hiroyuki; Watanabe, Tsuyoshi; Shimabukuro, Michio

2018-01-01

The cross talk between the adipose tissue and insulin target tissues is a key mechanism for obesity-associated insulin resistance. However, the precise role of the interaction between the skeletal muscle and adipose tissue for insulin signaling and glucose uptake is questionable. L6 myocytes were co-cultured with or without 3T3-L1 adipocytes (~5 × 10 3 cells/cm 2 ) up to 24 h. Glucose uptake was evaluated by 2-[ 3 H] deoxyglucose uptake assay. Levels of mRNA expression of Glut1 and Glut4 and mitochondrial enzymes were analyzed by quantitative real-time reverse transcription polymerase chain reaction. Levels of Glut1 and Glut4 protein and phosphorylation of Akt (Ser473 and Thr308) were analyzed by immunoblotting. Study 1: co-culture with 3T3-L1 adipocytes increased glucose uptake in dose- and time-dependent manner in L6 myocytes under insulin-untreated conditions. When co-cultured with 3T3-L1 cells, reactive oxygen species production and levels of Glut1 mRNA and protein were increased in L6 cells, while these changes were abrogated and the glucose uptake partially inhibited by antioxidant treatment. Study 2: co-culture with 3T3-L1 adipocytes suppressed insulin-stimulated glucose uptake in L6 myocytes. Insulin-induced Akt phosphorylation at Ser473 decreased, which was proportional to 3T3-L1 density. Antioxidant treatment partially reversed this effect. Interactions between skeletal muscle and adipose tissues are important for glucose uptake under insulin-untreated or -treated condition through oxygen stress mechanism.

Lipid accumulation in smooth muscle cells under LDL loading is independent of LDL receptor pathway and enhanced by hypoxic conditions.

PubMed

Wada, Youichiro; Sugiyama, Akira; Yamamoto, Takashi; Naito, Makoto; Noguchi, Noriko; Yokoyama, Shinji; Tsujita, Maki; Kawabe, Yoshiki; Kobayashi, Mika; Izumi, Akashi; Kohro, Takahide; Tanaka, Toshiya; Taniguchi, Hirokazu; Koyama, Hidenori; Hirano, Ken-ichi; Yamashita, Shizuya; Matsuzawa, Yuji; Niki, Etsuo; Hamakubo, Takao; Kodama, Tatsuhiko

2002-10-01

The effect of a variety of hypoxic conditions on lipid accumulation in smooth muscle cells (SMCs) was studied in an arterial wall coculture and monocultivation model. Low density lipoprotein (LDL) was loaded under various levels of oxygen tension. Oil red O staining of rabbit and human SMCs revealed that lipid accumulation was greater under lower oxygen tension. Cholesterol esters were shown to accumulate in an oxygen tension-dependent manner by high-performance liquid chromatographic analysis. Autoradiograms using radiolabeled LDL indicated that LDL uptake was more pronounced under hypoxia. This result holds in the case of LDL receptor-deficient rabbit SMCs. However, cholesterol biosynthesis and cellular cholesterol release were unaffected by oxygen tension. Hypoxia significantly increases LDL uptake and enhances lipid accumulation in arterial SMCs, exclusive of LDL receptor activity. Although the molecular mechanism is not clear, the model is useful for studying lipid accumulation in arterial wall cells and the difficult-to-elucidate events in the initial stage of atherogenesis.

Impaired systemic oxygen extraction in treated exercise pulmonary hypertension: a new engine in an old car?

PubMed

Faria-Urbina, Mariana; Oliveira, Rudolf K F; Segrera, Sergio A; Lawler, Laurie; Waxman, Aaron B; Systrom, David M

2018-01-01

Ambrisentan in 22 patients with pulmonary hypertension diagnosed during exercise (ePH) improved pulmonary hemodynamics; however, there was only a trend toward increased maximum oxygen uptake (VO 2 max) secondary to decreased maximum exercise systemic oxygen extraction (Ca-vO 2 ). We speculate that improved pulmonary hemodynamics at maximum exercise "unmasked" a pre-existing skeletal muscle abnormality.

Prediction of maximal oxygen uptake by bioelectrical impedance analysis in overweight adolescents.

PubMed

Roberts, M D; Drinkard, B; Ranzenhofer, L M; Salaita, C G; Sebring, N G; Brady, S M; Pinchbeck, C; Hoehl, J; Yanoff, L B; Savastano, D M; Han, J C; Yanovski, J A

2009-09-01

Maximal oxygen uptake (VO(2max)), the gold standard for measurement of cardiorespiratory fitness, is frequently difficult to assess in overweight individuals due to physical limitations. Reactance and resistance measures obtained from bioelectrical impedance analysis (BIA) have been suggested as easily obtainable predictors of cardiorespiratory fitness, but the accuracy with which ht(2)/Z can predict VO(2max) has not previously been examined in overweight adolescents. The impedance index was used as a predictor of VO(2max) in 87 overweight girls and 47 overweight boys ages 12 to 17 with mean BMI of 38.6 + or - 7.3 and 42.5 + or - 8.2 in girls and boys respectively. The Bland Altman procedure assessed agreement between predicted and actual VO(2max). Predicted VO(2max) was significantly correlated with measured VO(2max) (r(2)=0.48, P<0.0001). Using the Bland Altman procedure, there was significant magnitude bias (r(2)=0.10; P<0.002). The limits of agreement for predicted relative to actual VO(2max) were -589 to 574 mL O(2)/min. The impedance index was highly correlated with VO(2max) in overweight adolescents. However, using BIA data to predict maximal oxygen uptake over-predicted VO(2max) at low levels of oxygen consumption and under-predicted VO(2max) at high levels of oxygen consumption. This magnitude bias, along with the large limits of agreement of BIA-derived predicted VO(2max), limit its usefulness in the clinical setting for overweight adolescents.

40 CFR 503.31 - Special definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 503.31 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SEWAGE SLUDGE STANDARDS... microorganisms in the absence of air. (c) Density of microorganisms is the number of microorganisms per unit mass...) Specific oxygen uptake rate (SOUR) is the mass of oxygen consumed per unit time per unit mass of total...

Evaluation of oxidation behavior of γ-irradiated EPDM/PP compounds

NASA Astrophysics Data System (ADS)

Zaharescu, T.; Jipa, S.; Setnescu, R.; Setnescu, T.

2007-12-01

The oxidation effect of irradiation on ethylene-propylene diene terpolymer/polypropylene blends is presented. The polymer samples consisting of both materials under various ratios (20:80, 40:60, 60:40 and 80:20) were exposed to γ-irradiation ( 137Cs). The irradiation effects were assessed by two methods: oxygen uptake and IR spectroscopy (1720 cm -1 and 3350 cm -1, the characteristic bands for carbonyl and hydroxyl groups, respectively). The carbonyl and hydroxyl indexes were calculated for all formulations. From oxygen uptake investigation the kinetic parameters for thermal oxidation of irradiated samples were calculated. The contribution of each component to the progress of degradation is discussed.

Exercise physiology in heart failure and preserved ejection fraction.

PubMed

Haykowsky, Mark J; Kitzman, Dalane W

2014-07-01

Recent advances in the pathophysiology of exercise intolerance in patients with heart failure with preserved ejection fraction (HFPEF) suggest that noncardiac peripheral factors contribute to the reduced peak V(o2) (peak exercise oxygen uptake) and to its improvement after endurance exercise training. A greater understanding of the peripheral skeletal muscle vascular adaptations that occur with physical conditioning may allow for tailored exercise rehabilitation programs. The identification of specific mechanisms that improve whole body and peripheral skeletal muscle oxygen uptake could establish potential therapeutic targets for medical therapies and a means to follow therapeutic response. Copyright © 2014 Elsevier Inc. All rights reserved.

Genetic variants of uncoupling proteins-2 and -3 in relation to maximal oxygen uptake in different sports.

PubMed

Holdys, Joanna; Gronek, Piotr; Kryściak, Jakub; Stanisławski, Daniel

2013-01-01

Uncoupling proteins 2 and 3 (UCP2 and UCP3) as mitochondrial electron transporters are involved in regulation of ATP production and energy dissipation as heat. Energy efficiency plays an important role in physical performance, especially in aerobic fitness. The aim of this study was to examine the association between maximal oxygen uptake and genetic variants of the UCP2 and UCP3 genes. The studies were carried out in a group of 154 men and 85 women, professional athletes representing various sports and fitness levels and students of the University of Physical Education in Poznań. Physiological and molecular procedures were used, i.e. direct measurement of maximum oxygen uptake (VO₂max) and analysis of an insertion/deletion (I/D) polymorphism in the 3'untranslated region of exon 8 of the UCP2 gene and a C>T substitution in exon 5 (Y210Y) of the UCP3 gene. No statistically significant associations were found, only certain trends. Insertion allele (I) of the I/D UCP2 and the T allele of the UCP3 gene were favourable in obtaining higher VO₂max level and might be considered as endurance-related alleles.

The role of necrosis, acute hypoxia and chronic hypoxia in 18F-FMISO PET image contrast: a computational modelling study

NASA Astrophysics Data System (ADS)

Warren, Daniel R.; Partridge, Mike

2016-12-01

Positron emission tomography (PET) using 18F-fluoromisonidazole (FMISO) is a promising technique for imaging tumour hypoxia, and a potential target for radiotherapy dose-painting. However, the relationship between FMISO uptake and oxygen partial pressure ({{P}{{\\text{O}2}}} ) is yet to be quantified fully. Tissue oxygenation varies over distances much smaller than clinical PET resolution (<100 μm versus  ˜4 mm), and cyclic variations in tumour perfusion have been observed on timescales shorter than typical FMISO PET studies (˜20 min versus a few hours). Furthermore, tracer uptake may be decreased in voxels containing some degree of necrosis. This work develops a computational model of FMISO uptake in millimetre-scale tumour regions. Coupled partial differential equations govern the evolution of oxygen and FMISO distributions, and a dynamic vascular source map represents temporal variations in perfusion. Local FMISO binding capacity is modulated by the necrotic fraction. Outputs include spatiotemporal maps of {{P}{{\\text{O}2}}} and tracer accumulation, enabling calculation of tissue-to-blood ratios (TBRs) and time-activity curves (TACs) as a function of mean tissue oxygenation. The model is characterised using experimental data, finding half-maximal FMISO binding at local {{P}{{\\text{O}2}}} of 1.4 mmHg (95% CI: 0.3-2.6 mmHg) and half-maximal necrosis at 1.2 mmHg (0.1-4.9 mmHg). Simulations predict a non-linear non-monotonic relationship between FMISO activity (4 hr post-injection) and mean tissue {{P}{{\\text{O}2}}} : tracer uptake rises sharply from negligible levels in avascular tissue, peaking at  ˜5 mmHg and declining towards blood activity in well-oxygenated conditions. Greater temporal variation in perfusion increases peak TBRs (range 2.20-5.27) as a result of smaller predicted necrotic fraction, rather than fundamental differences in FMISO accumulation under acute hypoxia. Identical late FMISO uptake can occur in regions with differing {{P}{{\\text{O}2}}} and necrotic fraction, but simulated TACs indicate that additional early-phase information may allow discrimination of hypoxic and necrotic signals. We conclude that a robust approach to FMISO interpretation (and dose-painting prescription) is likely to be based on dynamic PET analysis.

The role of necrosis, acute hypoxia and chronic hypoxia in 18F-FMISO PET image contrast: a computational modelling study.

PubMed

Warren, Daniel R; Partridge, Mike

2016-12-21

Positron emission tomography (PET) using 18 F-fluoromisonidazole (FMISO) is a promising technique for imaging tumour hypoxia, and a potential target for radiotherapy dose-painting. However, the relationship between FMISO uptake and oxygen partial pressure ([Formula: see text]) is yet to be quantified fully. Tissue oxygenation varies over distances much smaller than clinical PET resolution (<100 μm versus  ∼4 mm), and cyclic variations in tumour perfusion have been observed on timescales shorter than typical FMISO PET studies (∼20 min versus a few hours). Furthermore, tracer uptake may be decreased in voxels containing some degree of necrosis. This work develops a computational model of FMISO uptake in millimetre-scale tumour regions. Coupled partial differential equations govern the evolution of oxygen and FMISO distributions, and a dynamic vascular source map represents temporal variations in perfusion. Local FMISO binding capacity is modulated by the necrotic fraction. Outputs include spatiotemporal maps of [Formula: see text] and tracer accumulation, enabling calculation of tissue-to-blood ratios (TBRs) and time-activity curves (TACs) as a function of mean tissue oxygenation. The model is characterised using experimental data, finding half-maximal FMISO binding at local [Formula: see text] of 1.4 mmHg (95% CI: 0.3-2.6 mmHg) and half-maximal necrosis at 1.2 mmHg (0.1-4.9 mmHg). Simulations predict a non-linear non-monotonic relationship between FMISO activity (4 hr post-injection) and mean tissue [Formula: see text] : tracer uptake rises sharply from negligible levels in avascular tissue, peaking at  ∼5 mmHg and declining towards blood activity in well-oxygenated conditions. Greater temporal variation in perfusion increases peak TBRs (range 2.20-5.27) as a result of smaller predicted necrotic fraction, rather than fundamental differences in FMISO accumulation under acute hypoxia. Identical late FMISO uptake can occur in regions with differing [Formula: see text] and necrotic fraction, but simulated TACs indicate that additional early-phase information may allow discrimination of hypoxic and necrotic signals. We conclude that a robust approach to FMISO interpretation (and dose-painting prescription) is likely to be based on dynamic PET analysis.

At-Sea Test and Evaluation Of Oxygen (O2) Analyzers.

DTIC Science & Technology

1981-04-01

Paramagnetic Oxygen Analyzer 2-6 2.4 Thermomagnetic Oxygen Analyzer Sensor 2-8 2.5 Cell Voltage versus Oxygen Concentration at 2-11 Various Cell ...of flue gas out of the stack across the cell and back into the stack. In-situ units place the cell directly in the flue gas path in the uptake. ) The...repetitive failurc of a cell heater temperature control circuit and a control cabinet electron- ic malfunction. Of the five (5) units that remained in

Diurnal Variations in Maximal Oxygen Uptake.

ERIC Educational Resources Information Center

McClellan, Powell D.

A study attempted to determine if diurnal (daily cyclical) variations were present during maximal exercise. The subjects' (30 female undergraduate physical education majors) oxygen consumption and heart rates were monitored while they walked on a treadmill on which the grade was raised every minute. Each subject was tested for maximal oxygen…

Lrp5 Has a Wnt-Independent Role in Glucose Uptake and Growth for Mammary Epithelial Cells

PubMed Central

Chin, Emily N.; Martin, Joshua A.; Kim, Soyoung; Fakhraldeen, Saja A.

2015-01-01

Lrp5 is typically described as a Wnt signaling receptor, albeit a less effective Wnt signaling receptor than the better-studied sister isoform, Lrp6. Here we show that Lrp5 is only a minor player in the response to Wnt3a-type ligands in mammary epithelial cells; instead, Lrp5 is required for glucose uptake, and glucose uptake regulates the growth rate of mammary epithelial cells in culture. Thus, a loss of Lrp5 leads to profound growth suppression, whether growth is induced by serum or by specific growth factors, and this inhibition is not due to a loss of Wnt signaling. Depletion of Lrp5 decreases glucose uptake, lactate secretion, and oxygen consumption rates; inhibition of glucose consumption phenocopies the loss of Lrp5 function. Both Lrp5 knockdown and low external glucose induce mitochondrial stress, as revealed by the accumulation of reactive oxygen species (ROS) and the activation of the ROS-sensitive checkpoint, p38α. In contrast, loss of function of Lrp6 reduces Wnt responsiveness but has little impact on growth. This highlights the distinct functions of these two Lrp receptors and an important Wnt ligand-independent role of Lrp5 in glucose uptake in mammary epithelial cells. PMID:26711269

Exercise modality effect on oxygen uptake off-transient kinetics at maximal oxygen uptake intensity.

PubMed

Sousa, Ana; Rodríguez, Ferran A; Machado, Leandro; Vilas-Boas, J Paulo; Fernandes, Ricardo J

2015-06-01

What is the central question of this study? Do the mechanical differences between swimming, rowing, running and cycling have a potential effect on the oxygen uptake (V̇O2) off-kinetics after an exercise sustained until exhaustion at 100% of maximal oxygen uptake (V̇O2max) intensity? What is the main finding and its importance? The mechanical differences between exercise modes had a potential effect and contributed to distinct amplitude of the fast component (higher in running compared with cycling) and time constant (higher in swimming compared with rowing and cycling) in the V̇O2 off-kinetic patterns at 100% of V̇O2max intensity. This suggests that swimmers, unlike rowers and cyclists, would benefit more from a longer duration of training intervals after each set of exercise performed at V̇O2max intensity. The kinetics of oxygen uptake (V̇O2) during recovery (off-transient kinetics) for different exercise modes is largely unexplored, hampering the prescription of training and recovery to enhance performance. The purpose of this study was to compare the V̇O2 off-transient kinetics response between swimmers, rowers, runners and cyclists during their specific mode of exercise at 100% of maximal oxygen uptake (V̇O2max) intensity and to examine the on-off symmetry. Groups of swimmers, rowers, runners and cyclists (n = 8 per group) performed (i) an incremental exercise protocol to assess the velocity or power associated with V̇O2max (vV̇O2max or wV̇O2max, respectively) and (ii) a square-wave exercise transition from rest to vV̇O2max/vV̇O2maxwV̇O2maxwV̇O2max until volitional exhaustion. Pulmonary exchange parameters were measured using a telemetric portable gas analyser (K4b(2) ; Cosmed, Rome, Italy), and the on- and off-transient kinetics were analysed through a double-exponential approach. For all exercise modes, both transient periods were symmetrical in shape once they had both been adequately fitted by a double-exponential model. However, differences were found in the off-kinetic parameters between exercise modes; the amplitude of the fast component of the V̇O2 off-response was higher in running compared with cycling (48 ± 5 and 36 ± 7 ml kg(-1) min(-1) , respectively; P < 0.001), and the time constant of the same phase was higher in swimming compared with rowing and cycling (63 ± 5, 56 ± 5 and 55 ± 3 s, respectively; P < 0.001). Although both phases were well described by a double-exponential model, the differences between exercise modes had a potential effect and contributed to distinct V̇O2 off-transient kinetic patterns at 100% of V̇O2max intensity. © 2015 The Authors. Experimental Physiology © 2015 The Physiological Society.

Hypoxic Response of Tumor Tissues in a Microfluidic Environment

NASA Astrophysics Data System (ADS)

Morshed, Adnan; Dutta, Prashanta

2017-11-01

Inside a tumor tissue, cells growing further away from the blood vessel often suffer from low oxygen levels known as hypoxia. Cancer cells have shown prolonged survival in hostile hypoxic conditions by sharply changing the cellular metabolism. In this work, different stages of growth of the tumor tissue and the oxygen transport across the tissue are investigated. The tissue was modeled as a contiguous block of cells inside a microfluidic environment with nutrient transport through advection and diffusion. While oxygen uptake inside the tissue is through diffusion, ascorbate transport from the extracellular medium is addressed by a concentration dependent uptake model. By varying the experimentally observed oxygen consumption rate, different types of cancer cells and their normoxic and hypoxic stages were studied. Even when the oxygen supply in the channel is maintained at normoxic levels, our results show the onset of hypoxia within minutes inside the cellblock. Interestingly, modeled cell blocks with and without a structured basal layer showed less than 5% variation in hypoxic response in chronic hypoxia. Results also indicate that the balance of cell survival and growth are affected by the flow rate of nutrients and the oxygen consumption rate. This work was supported in part by the National Science Foundation under Grant No. DMS 1317671.

Real‐time monitoring of specific oxygen uptake rates of embryonic stem cells in a microfluidic cell culture device

PubMed Central

Super, Alexandre; Jaccard, Nicolas; Cardoso Marques, Marco Paulo; Macown, Rhys Jarred; Griffin, Lewis Donald; Veraitch, Farlan Singh

2016-01-01

Abstract Oxygen plays a key role in stem cell biology as a signaling molecule and as an indicator of cell energy metabolism. Quantification of cellular oxygen kinetics, i.e. the determination of specific oxygen uptake rates (sOURs), is routinely used to understand metabolic shifts. However current methods to determine sOUR in adherent cell cultures rely on cell sampling, which impacts on cellular phenotype. We present real‐time monitoring of cell growth from phase contrast microscopy images, and of respiration using optical sensors for dissolved oxygen. Time‐course data for bulk and peri‐cellular oxygen concentrations obtained for Chinese hamster ovary (CHO) and mouse embryonic stem cell (mESCs) cultures successfully demonstrated this non‐invasive and label‐free approach. Additionally, we confirmed non‐invasive detection of cellular responses to rapidly changing culture conditions by exposing the cells to mitochondrial inhibiting and uncoupling agents. For the CHO and mESCs, sOUR values between 8 and 60 amol cell−1 s−1, and 5 and 35 amol cell−1 s−1 were obtained, respectively. These values compare favorably with literature data. The capability to monitor oxygen tensions, cell growth, and sOUR, of adherent stem cell cultures, non‐invasively and in real time, will be of significant benefit for future studies in stem cell biology and stem cell‐based therapies. PMID:27214658

The diffusive boundary layer of sediments: oxygen microgradients over a microbial mat

NASA Technical Reports Server (NTRS)

Jorgensen, B. B.; Des Marais, D. J.

1990-01-01

Oxygen microelectrodes were used to analyze the distribution of the diffusive boundary layer (DBL) at the sediment-water interface in relation to surface topography and flow velocity. The sediment, collected from saline ponds, was covered by a microbial mat that had high oxygen consumption rate and well-defined surface structure. Diffusion through the DBL constituted an important rate limitation to the oxygen uptake of the sediment. The mean effective DBL thickness decreased from 0.59 to 0.16 mm as the flow velocity of the overlying water was increased from 0.3 to 7.7 cm s-1 (measured 1 cm above the mat). The oxygen uptake rate concurrently increased from 3.9 to 9.4 nmol cm-2 min-1. The effects of surface roughness and topography on the thickness and distribution of the DBL were studied by three-dimensional mapping of the sediment-water interface and the upper DBL boundary at 0.1-mm spatial resolution. The DBL boundary followed mat structures that had characteristic dimensions > 1/2 DBL thickness but the DBL had a dampened relief relative to the mat. The effective surface area of the sediment-water interface and of the upper DBL boundary were 31 and 14% larger, respectively, than a flat plane. Surface topography thereby increased the oxygen flux across the sediment-water interface by 49% relative to a one-dimensional diffusion flux calculated from the vertical oxygen microgradients.

The response of the tidepool sculpin, Oligocottus maculosus, to hypoxia in laboratory, mesocosm and field environments.

PubMed

Sloman, Katherine A; Mandic, Milica; Todgham, Anne E; Fangue, Nann A; Subrt, Peter; Richards, Jeffrey G

2008-03-01

Animals living in the intertidal zone experience regular, predictable fluctuations in physical parameters including temperature, oxygen and salinity and rely on behavioural, physiological and biochemical mechanisms to cope with environmental variation. In the present study, behavioural strategies induced by aquatic hypoxia (e.g. emergence) were performed at similar oxygen tensions across laboratory, mesocosm and field environments; the number of individuals performing these behaviours at any one time was similar in mesocosms and the field. The use of aquatic surface respiration (ASR) was more plastic than emergence behaviour, occurring at a lower oxygen tension in juveniles than adults and being influenced by the addition of alarm substance. Oxygen uptake was lower in air than in water in adults but, in contrast, oxygen uptake was not influenced by the respiratory medium in juveniles. In the laboratory, 72 h of forced emergence did not affect whole body concentrations of lactate but when ASR and emergence were prevented within mesocosm environments there was a significant elevation of lactate. The present study highlights the benefits of transcending traditional laboratory/field boundaries allowing the responses of laboratory-held animals to environmental fluctuation to be integrated with how these animals perform in their natural environment.

A Comparative Study of the Hypoxia PET Tracers [{sup 18}F]HX4, [{sup 18}F]FAZA, and [{sup 18}F]FMISO in a Preclinical Tumor Model

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

Peeters, Sarah G.J.A., E-mail: sarah.peeters@maastrichtuniversity.nl; Zegers, Catharina M.L.; Lieuwes, Natasja G.

Purpose: Several individual clinical and preclinical studies have shown the possibility of evaluating tumor hypoxia by using noninvasive positron emission tomography (PET). The current study compared 3 hypoxia PET tracers frequently used in the clinic, [{sup 18}F]FMISO, [{sup 18}F]FAZA, and [{sup 18}F]HX4, in a preclinical tumor model. Tracer uptake was evaluated for the optimal time point for imaging, tumor-to-blood ratios (TBR), spatial reproducibility, and sensitivity to oxygen modification. Methods and Materials: PET/computed tomography (CT) images of rhabdomyosarcoma R1-bearing WAG/Rij rats were acquired at multiple time points post injection (p.i.) with one of the hypoxia tracers. TBR values were calculated, andmore » reproducibility was investigated by voxel-to-voxel analysis, represented as correlation coefficients (R) or Dice similarity coefficient of the high-uptake volume. Tumor oxygen modifications were induced by exposure to either carbogen/nicotinamide treatment or 7% oxygen breathing. Results: TBR was stabilized and maximal at 2 hours p.i. for [{sup 18}F]FAZA (4.0 ± 0.5) and at 3 hours p.i. for [{sup 18}F]HX4 (7.2 ± 0.7), whereas [{sup 18}F]FMISO showed a constant increasing TBR (9.0 ± 0.8 at 6 hours p.i.). High spatial reproducibility was observed by voxel-to-voxel comparisons and Dice similarity coefficient calculations on the 30% highest uptake volume for both [{sup 18}F]FMISO (R = 0.86; Dice coefficient = 0.76) and [{sup 18}F]HX4 (R = 0.76; Dice coefficient = 0.70), whereas [{sup 18}F]FAZA was less reproducible (R = 0.52; Dice coefficient = 0.49). Modifying the hypoxic fraction resulted in enhanced mean standardized uptake values for both [{sup 18}F]HX4 and [{sup 18}F]FAZA upon 7% oxygen breathing. Only [{sup 18}F]FMISO uptake was found to be reversible upon exposure to nicotinamide and carbogen. Conclusions: This study indicates that each tracer has its own strengths and, depending on the question to be answered, a different tracer can be put forward.« less

Changes in sevoflurane plasma concentration with delivery through the oxygenator during on-pump cardiac surgery.

PubMed

Nitzschke, R; Wilgusch, J; Kersten, J F; Trepte, C J; Haas, S A; Reuter, D A; Goetz, A E; Goepfert, M S

2013-06-01

It is unclear what factors affect the uptake of sevoflurane administered through the membrane oxygenator during cardiopulmonary bypass (CPB) and whether this can be monitored via the oxygenator exhaust gas. Stable delivery of sevoflurane was administered to 30 elective cardiac surgery patients at 1.8 vol% (inspiratory) via the anaesthetic circuit and ventilator. During CPB, sevoflurane was administered in the oxygenator fresh gas supply (Compactflo Evolution™; Sorin Group, Milano, Italy). Sevoflurane plasma concentration (SPC) was measured using gas chromatography. Changes were correlated with bispectral index (BIS), patient temperature, haematocrit, plasma albumin concentration, oxygenator fresh gas flow, and the sevoflurane concentration in the oxygenator exhaust at predefined time points. The mean SPC pre-bypass was 54.9 µg ml(-1) [95% confidence interval (CI): 50.6-59.1]. SPC decreased to 43.2 µg ml(-1) (95% CI: 40.3-46.1; P<0.001) after initiation of CPB, and was lower still during rewarming and weaning from bypass, 39.4 µg ml(-1) (95% CI: 36.6-42.3; P<0.001). BIS did not exceed a value of 55. SPCs were higher during hypothermia (P<0.001) and with an increase in oxygenator fresh gas flow (P=0.015), and lower with haemodilution (P=0.027). No correlation was found between SPC and the concentration of sevoflurane in the oxygenator exhaust gas (r=-0.04; 95% CI: -0.18 to 0.09; P=0.53). The uptake of sevoflurane delivered via the membrane oxygenator during CPB seems to be affected by hypothermia, haemodilution, and changes in the oxygenator fresh gas supply flow. Measuring the concentration of sevoflurane in the exhaust from the oxygenator is not useful for monitoring sevoflurane administration during bypass.

Critical soil conditions for oxygen stress to plant roots: Substituting the Feddes-function by a process-based model

NASA Astrophysics Data System (ADS)

Bartholomeus, Ruud P.; Witte, Jan-Philip M.; van Bodegom, Peter M.; van Dam, Jos C.; Aerts, Rien

2008-10-01

SummaryEffects of insufficient soil aeration on the functioning of plants form an important field of research. A well-known and frequently used utility to express oxygen stress experienced by plants is the Feddes-function. This function reduces root water uptake linearly between two constant pressure heads, representing threshold values for minimum and maximum oxygen deficiency. However, the correctness of this expression has never been evaluated and constant critical values for oxygen stress are likely to be inappropriate. On theoretical grounds it is expected that oxygen stress depends on various abiotic and biotic factors. In this paper, we propose a fundamentally different approach to assess oxygen stress: we built a plant physiological and soil physical process-based model to calculate the minimum gas filled porosity of the soil ( ϕgas_min) at which oxygen stress occurs. First, we calculated the minimum oxygen concentration in the gas phase of the soil needed to sustain the roots through (micro-scale) diffusion with just enough oxygen to respire. Subsequently, ϕgas_min that corresponds to this minimum oxygen concentration was calculated from diffusion from the atmosphere through the soil (macro-scale). We analyzed the validity of constant critical values to represent oxygen stress in terms of ϕgas_min, based on model simulations in which we distinguished different soil types and in which we varied temperature, organic matter content, soil depth and plant characteristics. Furthermore, in order to compare our model results with the Feddes-function, we linked root oxygen stress to root water uptake (through the sink term variable F, which is the ratio of actual and potential uptake). The simulations showed that ϕgas_min is especially sensitive to soil temperature, plant characteristics (root dry weight and maintenance respiration coefficient) and soil depth but hardly to soil organic matter content. Moreover, ϕgas_min varied considerably between soil types and was larger in sandy soils than in clayey soils. We demonstrated that F of the Feddes-function indeed decreases approximately linearly, but that actual oxygen stress already starts at drier conditions than according to the Feddes-function. How much drier is depended on the factors indicated above. Thus, the Feddes-function might cause large errors in the prediction of transpiration reduction and growth reduction through oxygen stress. We made our method easily accessible to others by implementing it in SWAP, a user-friendly soil water model that is coupled to plant growth. Since constant values for ϕgas_min in plant and hydrological modeling appeared to be inappropriate, an integrated approach, including both physiological and physical processes, should be used instead. Therefore, we advocate using our method in all situations where oxygen stress could occur.

Temporal dissociation between muscle and pulmonary oxygen uptake kinetics: influences of perfusion dynamics and arteriovenous oxygen concentration differences in muscles and lungs.

PubMed

Drescher, U; Koschate, J; Thieschäfer, L; Schneider, S; Hoffmann, U

2018-06-22

The aim of the study was to test whether or not the arteriovenous oxygen concentration difference (avDO 2 ) kinetics at the pulmonary (avDO 2 pulm) and muscle (avDO 2 musc) levels is significantly different during dynamic exercise. A re-analysis involving six publications dealing with kinetic analysis was utilized with an overall sample size of 69 participants. All studies comprised an identical pseudorandom binary sequence work rate (WR) protocol-WR changes between 30 and 80 W-to analyze the kinetic responses of pulmonary ([Formula: see text]) and muscle ([Formula: see text]) oxygen uptake kinetics as well as those of avDO 2 pulm and avDO 2 musc. A significant difference between [Formula: see text] (0.395 ± 0.079) and [Formula: see text] kinetics (0.330 ± 0.078) was observed (p < 0.001), where the variables showed a significant relationship (r SP  = 0.744, p < 0.001). There were no significant differences between avDO 2 musc (0.446 ± 0.077) and avDO 2 pulm kinetics (0.451 ± 0.075), which are highly correlated (r = 0.929, p < 0.001). It is suggested that neither avDO 2 pulm nor avDO 2 musc kinetic responses seem to be responsible for the differences between estimated [Formula: see text] and measured [Formula: see text] kinetics. Obviously, the conflation of avDO 2 and perfusion ([Formula: see text] ) at different points in time and at different physiological levels drive potential differences in [Formula: see text] and [Formula: see text] kinetics. Therefore, [Formula: see text] should, in general, be considered whenever oxygen uptake kinetics are analyzed or discussed.

Enhanced Heme Function and Mitochondrial Respiration Promote the Progression of Lung Cancer Cells

PubMed Central

Alam, Md Maksudul; Shah, Ajit; Cao, Thai M.; Sullivan, Laura A.; Brekken, Rolf; Zhang, Li

2013-01-01

Lung cancer is the leading cause of cancer-related mortality, and about 85% of the cases are non-small-cell lung cancer (NSCLC). Importantly, recent advance in cancer research suggests that altering cancer cell bioenergetics can provide an effective way to target such advanced cancer cells that have acquired mutations in multiple cellular regulators. This study aims to identify bioenergetic alterations in lung cancer cells by directly measuring and comparing key metabolic activities in a pair of cell lines representing normal and NSCLC cells developed from the same patient. We found that the rates of oxygen consumption and heme biosynthesis were intensified in NSCLC cells. Additionally, the NSCLC cells exhibited substantially increased levels in an array of proteins promoting heme synthesis, uptake and function. These proteins include the rate-limiting heme biosynthetic enzyme ALAS, transporter proteins HRG1 and HCP1 that are involved in heme uptake, and various types of oxygen-utilizing hemoproteins such as cytoglobin and cytochromes. Several types of human tumor xenografts also displayed increased levels of such proteins. Furthermore, we found that lowering heme biosynthesis and uptake, like lowering mitochondrial respiration, effectively reduced oxygen consumption, cancer cell proliferation, migration and colony formation. In contrast, lowering heme degradation does not have an effect on lung cancer cells. These results show that increased heme flux and function are a key feature of NSCLC cells. Further, increased generation and supply of heme and oxygen-utilizing hemoproteins in cancer cells will lead to intensified oxygen consumption and cellular energy production by mitochondrial respiration, which would fuel cancer cell proliferation and progression. The results show that inhibiting heme and respiratory function can effectively arrest the progression of lung cancer cells. Hence, understanding heme function can positively impact on research in lung cancer biology and therapeutics. PMID:23704904

Fish embryos on land: terrestrial embryo deposition lowers oxygen uptake without altering growth or survival in the amphibious fish Kryptolebias marmoratus.

PubMed

Wells, Michael W; Turko, Andy J; Wright, Patricia A

2015-10-01

Few teleost fishes incubate embryos out of water, but the oxygen-rich terrestrial environment could provide advantages for early growth and development. We tested the hypothesis that embryonic oxygen uptake is limited in aquatic environments relative to air using the self-fertilizing amphibious mangrove rivulus, Kryptolebias marmoratus, which typically inhabits hypoxic, water-filled crab burrows. We found that adult mangrove rivulus released twice as many embryos in terrestrial versus aquatic environments and that air-reared embryos had accelerated developmental rates. Surprisingly, air-reared embryos consumed 44% less oxygen and possessed larger yolk reserves, but attained the same mass, length and chorion thickness. Water-reared embryos moved their opercula ∼2.5 more times per minute compared with air-reared embryos at 7 days post-release, which probably contributed to the higher rates of oxygen uptake and yolk utilization we observed. Genetically identical air- and water-reared embryos from the same parent were raised to maturity, but the embryonic environment did not affect growth, reproduction or emersion ability in adults. Therefore, although aspects of early development were plastic, these early differences were not sustained into adulthood. Kryptolebias marmoratus embryos hatched out of water when exposed to aerial hypoxia. We conclude that exposure to a terrestrial environment reduces the energetic costs of development partly by reducing the necessity of embryonic movements to dispel stagnant boundary layers. Terrestrial incubation of young would be especially beneficial to amphibious fishes that occupy aquatic habitats of poor water quality, assuming low terrestrial predation and desiccation risks. © 2015. Published by The Company of Biologists Ltd.

Oxygen in the Southern Ocean From Argo Floats: Determination of Processes Driving Air-Sea Fluxes

NASA Astrophysics Data System (ADS)

Bushinsky, Seth M.; Gray, Alison R.; Johnson, Kenneth S.; Sarmiento, Jorge L.

2017-11-01

The Southern Ocean is of outsized significance to the global oxygen and carbon cycles with relatively poor measurement coverage due to harsh winters and seasonal ice cover. In this study, we use recent advances in the parameterization of air-sea oxygen fluxes to analyze 9 years of oxygen data from a recalibrated Argo oxygen data set and from air-calibrated oxygen floats deployed as part of the Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) project. From this combined data set of 150 floats, we find a total Southern Ocean oxygen sink of -183 ± 80 Tmol yr-1 (positive to the atmosphere), greater than prior estimates. The uptake occurs primarily in the Polar-Frontal Antarctic Zone (PAZ, -94 ± 30 Tmol O2 yr-1) and Seasonal Ice Zone (SIZ, -111 ± 9.3 Tmol O2 yr-1). This flux is driven by wintertime ventilation, with a large portion of the flux in the SIZ passing through regions with fractional sea ice. The Subtropical Zone (STZ) is seasonally driven by thermal fluxes and exhibits a net outgassing of 47 ± 29 Tmol O2 yr-1 that is likely driven by biological production. The Subantarctic Zone (SAZ) uptake is -25 ± 12 Tmol O2 yr-1. Total oxygen fluxes were separated into a thermal and nonthermal component. The nonthermal flux is correlated with net primary production and mixed layer depth in the STZ, SAZ, and PAZ, but not in the SIZ where seasonal sea ice slows the air-sea gas flux response to the entrainment of deep, low-oxygen waters.

Caffeine inhibition of aflatoxin synthesis: probable site of action.

PubMed Central

Buchanan, R L; Lewis, D F

1984-01-01

Aflatoxin production by pregrown cultures of Aspergillus parasiticus was completely inhibited by incorporation of 2 mg of caffeine per ml into the medium. This was accompanied by a decrease in glucose utilization and an inhibition of oxygen uptake and carbon dioxide evolution. Enzyme analyses indicated no significant differences in specific activities on glucose-6-phosphate dehydrogenase, mannitol dehydrogenase, phosphofructokinase, fructose 1,6-diphosphatase, pyruvate kinase, or malate dehydrogenase. Glucose uptake kinetics indicated a linear dose-related inhibition of glucose uptake. It appears likely that caffeine inhibits aflatoxin synthesis by restricting the uptake of carbohydrates which are ultimately used by the mold to synthesize this family of mycotoxins. PMID:6331311

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…

Min-By-Min Respiratory Exchange and Oxygen Uptake Kinetics During Steady-State Exercise in Subjects of High and Low Max VO2

ERIC Educational Resources Information Center

Weltman, Arthur; Katch, Victor

1976-01-01

No statistically meaningful differences in steady-state vo2 uptake for high and low max vo2 groups was indicated in this study, but a clear tendency was observed for the high max vo2 group to reach the steady-state at a faster rate. (MB)

Low oxygen levels contribute to improve photohydrogen production in mixotrophic non-stressed Chlamydomonas cultures.

PubMed

Jurado-Oller, Jose Luis; Dubini, Alexandra; Galván, Aurora; Fernández, Emilio; González-Ballester, David

2015-01-01

Currently, hydrogen fuel is derived mainly from fossil fuels, but there is an increasing interest in clean and sustainable technologies for hydrogen production. In this context, the ability of some photosynthetic microorganisms, particularly cyanobacteria and microalgae, to produce hydrogen is a promising alternative for renewable, clean-energy production. Among a diverse array of photosynthetic microorganisms able to produce hydrogen, the green algae Chlamydomonas reinhardtii is the model organism widely used to study hydrogen production. Despite the well-known fact that acetate-containing medium enhances hydrogen production in this algae, little is known about the precise role of acetate during this process. We have examined several physiological aspects related to acetate assimilation in the context of hydrogen production metabolism. Measurements of oxygen and CO2 levels, acetate uptake, and cell growth were performed under different light conditions, and oxygenic regimes. We show that oxygen and light intensity levels control acetate assimilation and modulate hydrogen production. We also demonstrate that the determination of the contribution of the PSII-dependent hydrogen production pathway in mixotrophic cultures, using the photosynthetic inhibitor DCMU, can lead to dissimilar results when used under various oxygenic regimes. The level of inhibition of DCMU in hydrogen production under low light seems to be linked to the acetate uptake rates. Moreover, we highlight the importance of releasing the hydrogen partial pressure to avoid an inherent inhibitory factor on the hydrogen production. Low levels of oxygen allow for low acetate uptake rates, and paradoxically, lead to efficient and sustained production of hydrogen. Our data suggest that acetate plays an important role in the hydrogen production process, during non-stressed conditions, other than establishing anaerobiosis, and independent of starch accumulation. Potential metabolic pathways involved in hydrogen production in mixotrophic cultures are discussed. Mixotrophic nutrient-replete cultures under low light are shown to be an alternative for the simultaneous production of hydrogen and biomass.

Potential impact of Chironomus plumosus larvae on hypolimnetic oxygen in the central basin of Lake Erie

USGS Publications Warehouse

Soster, Frederick M.; Matisoff, Gerald; Schloesser, Donald W.; Edwards, William J.

2015-01-01

Previous studies have indicated that burrow-irrigating infauna can increase sediment oxygen demand (SOD) and impact hypolimnetic oxygen in stratified lakes. We conducted laboratory microcosm experiments and computer simulations with larvae of the burrowing benthic midge Chironomus plumosus to quantify burrow oxygen uptake rates and subsequent contribution to sediment oxygen demand in central Lake Erie. Burrow oxygen uptake and water flow velocities through burrows were measured using oxygen microelectrodes and hot film anemometry, respectively. Burrow oxygen consumption averaged 2.66 × 10− 10 (SE = ± 7.82 × 10− 11) mol O2/burrow/s at 24 °C and 9.64 × 10− 10 (SE = ± 4.86 × 10− 10) mol O2/burrow/s at 15 °C. In sealed microcosm experiments, larvae increased SOD 500% at 24 °C (density = 1508/m2) and 375% at 15 °C (density = 864/m2). To further evaluate effects of densities of C. plumosus burrows on SOD we developed a 3-D transport reaction model of the process. Using experimental data and chironomid abundance data in faunal surveys in 2009 and 2010, we estimated that bioirrigation by a population of 140 larvae/m2 could account for between 2.54 × 10− 11 mol/L/s (model results) and 5.58 × 10− 11 mol/L/s (experimental results) of the average 4.22 × 10− 11 mol/L/s oxygen depletion rate between 1970 and 2003, which could have accounted for 60–132% of the oxygen decline. At present, it appears that the population density of this species may be an important factor in development of hypoxic or anoxic conditions in central Lake Erie.

Specific physiological and biomechanical performance in elite, sub-elite and in non-elite male team handball players.

PubMed

Wagner, Herbert; Fuchs, Philip X; von Duvillard, Serge P

2018-01-01

Team handball is a dynamic sport game that is played professionally in numerous countries. However, knowledge about training and competition is based mostly on practical experience due to limited scientific studies. Consequently, the aims of our study were to compare specific physiological and biomechanical performance in elite, sub-elite and in non-elite male team handball players. Thirty-six elite, sub-elite and non-elite male team handball players performed a game based performance test, upper-body and lower-body strength tests, 30-m sprint test, counter movement jump test and an incremental treadmill running test. Significant differences (P<0.05) were found for the peak oxygen uptake, heart rate, offense and defense time, jump height and ball velocity during the jump throw in the game based performance test, maximal oxygen uptake in the incremental treadmill running test as well as in maximal leg strength and leg explosive strength in the isometric strength test. Elite male players have an enhanced specific agility, a better throwing performance, a higher team handball specific oxygen uptake and higher leg strength compared to sub-elite and non-elite players. Based on these results we recommend that training in team handball should focus on game based training methods to improve performance in specific agility, endurance and technique.

Evaluation of exercise capacity after severe stroke using robotics-assisted treadmill exercise: a proof-of-concept study.

PubMed

Stoller, O; de Bruin, E D; Schindelholz, M; Schuster, C; de Bie, R A; Hunt, K J

2013-01-01

Robotics-assisted treadmill exercise (RATE) with focus on motor recovery has become popular in early post-stroke rehabilitation but low endurance for exercise is highly prevalent in these individuals. This study aimed to develop an exercise testing method using robotics-assisted treadmill exercise to evaluate aerobic capacity after severe stroke. Constant load testing (CLT) based on body weight support (BWS) control, and incremental exercise testing (IET) based on guidance force (GF) control were implemented during RATE. Analyses focussed on step change, step response kinetics, and peak performance parameters of oxygen uptake. Three subjects with severe motor impairment 16-23 days post-stroke were included. CLT yielded reasonable step change values in oxygen uptake, whereas response kinetics of oxygen uptake showed low goodness of fit. Peak performance parameters were not obtained during IET. Exercise testing in post-stroke individuals with severe motor impairments using a BWS control strategy for CLT is deemed feasible and safe. Our approach yielded reasonable results regarding cardiovascular performance parameters. IET based on GF control does not provoke peak cardiovascular performance due to uncoordinated walking patterns. GF control needs further development to optimally demand active participation during RATE. The findings warrant further research regarding the evaluation of exercise capacity after severe stroke.

Plyometric exercise combined with high-intensity interval training improves metabolic abnormalities in young obese females more so than interval training alone.

PubMed

Racil, Ghazi; Zouhal, Hassane; Elmontassar, Wassim; Ben Abderrahmane, Abderraouf; De Sousa, Maysa Vieira; Chamari, Karim; Amri, Mohamed; Coquart, Jeremy B

2016-01-01

The aim of this study was to compare the effects of 12 weeks of high-intensity interval training (HIIT) with the effects of 12 weeks of plyometric exercise combined with HIIT (P+HIIT) on anthropometric, biochemical, and physical fitness data in young obese females. Sixty-eight participants (age, 16.6 ± 1.3 y; body mass, 82.8 ± 5.0 kg; body fat, 39.4% ± 3.3%; body mass index z score, 2.9 ± 0.4) were assigned to 1 of 3 groups: HIIT (2 blocks per session of 6-8 bouts of 30-s runs at 100% velocity at peak oxygen uptake, with 30-s active recovery between bouts at 50%velocity at peak oxygen uptake (n = 23)); P+HIIT (2 blocks per session of 3 different 15-s plyometric exercises with 15-s passive recoveries, totaling 2 min for each plyometric exercise + the same HIIT program (n = 26)); or control (no exercise (n = 19)). Anthropometric (body mass, body mass index z score, body fat, lean body mass, and waist circumference), biochemical (plasma glucose, insulin, leptin and adiponectin concentrations, leptin/adiponectin ratio, and homeostasis model assessment of insulin resistance (HOMA-IR)), physical fitness (peak oxygen uptake, velocity at peak oxygen uptake, squat jump, and countermovement jump performances), and energy intake data were collected. Both training programs improved the anthropometric, biochemical, and physical fitness variables. However, the P+HIIT program induced greater improvements than did the HIIT program in lean body mass (+3.0% ± 1.7%), plasma glucose and leptin concentrations (-11.0% ± 4.7% and -23.8% ± 5.8%, respectively), plasma leptin/adiponectin ratio (-40.9% ± 10.9%), HOMA-IR (-37.3% ± 6.2%), and squat jump performance (22.2% ± 7.5%). Taken together, these findings suggest that adding plyometric exercises to a HIIT program may be more beneficial than HIIT alone in obese female adolescents.

Negative impacts of elevated nitrate on physiological performance are not exacerbated by low pH.

PubMed

Gomez Isaza, Daniel F; Cramp, Rebecca L; Franklin, Craig E

2018-05-15

Multiple environmental stressors, including nutrient effluents (i.e. nitrates [NO 3 - ]) and altered pH regimes, influence the persistence of freshwater species in anthropogenically disturbed habitats. Independently, nitrate and low pH affect energy allocation by increasing maintenance costs and disrupting oxygen uptake, which ultimately results in impacts upon whole animal performance. However, the interaction between these two stressors has not been characterised. To address this, the effects of nitrate and pH and their interaction on aerobic scope and physiological performance were investigated in the blueclaw crayfish, Cherax destructor. Crayfish were exposed to a 2 × 3 factorial combination, with two pH levels (pH 5.0 and 7.0) and three nitrate concentrations (0, 50 and 100 mg L -1 NO 3 - ). Crayfish were exposed to experimental conditions for 65 days and growth and survival were monitored. Aerobic scope (i.e. maximal - standard oxygen uptake) was measured at six time points (1, 3, 5, 7, 14, and 21 days) during exposure to experimental treatments. Crayfish performance was assessed after 28 days, by measuring chelae strength and whole animal activity capacity via the righting response. Survival was reduced in crayfish exposed to pH 5.0, but there was no exacerbation of this effect by exposure to high nitrate levels. Aerobic scope was compromised by the interaction between low pH and nitrate and resulted in prolonged elevations of standard oxygen uptake rates. Exposure to nitrate alone affected aerobic scope, causing a 59% reduction in maximum oxygen uptake. Reduced aerobic capacity translated to reduced chelae strength and righting capacity. Together, these data show that low pH and elevated nitrate levels reduce aerobic scope and translate to poorer performance in C. destructor, which may have the potential to affect organismal fitness in disturbed habitats. Copyright © 2018 Elsevier B.V. All rights reserved.

Effects of macro- and micronutrients on exercise-induced hepcidin response in highly trained endurance athletes.

PubMed

Dahlquist, Dylan T; Stellingwerff, Trent; Dieter, Brad P; McKenzie, Donald C; Koehle, Michael S

2017-10-01

Iron deficiency has ergolytic effects on athletic performance. Exercise-induced inflammation impedes iron absorption in the digestive tract by upregulating the expression of the iron regulatory protein, hepcidin. Limited research indicates the potential of specific macro- and micronutrients on blunting exercise-induced hepcidin. Therefore, we investigated the effects of postexercise supplementation with protein and carbohydrate (CHO) and vitamins D 3 and K 2 on the postexercise hepcidin response. Ten highly trained male cyclists (age: 26.9 ± 6.4 years; maximal oxygen uptake: 67.4 ± 4.4 mL·kg -1 ·min -1 completed 4 cycling sessions in a randomized, placebo-controlled, single-blinded, triple-crossover study. Experimental days consisted of an 8-min warm-up at 50% power output at maximal oxygen uptake, followed by 8 × 3-min intervals at 85% power output at maximal oxygen uptake with 1.5 min at 60% power output at maximal oxygen uptake between each interval. Blood samples were collected pre- and postexercise, and at 3 h postexercise. Three different drinks consisting of CHO (75 g) and protein (25 g) with (VPRO) or without (PRO) vitamins D 3 (5000 IU) and K 2 (1000 μg), or a zero-calorie control drink (PLA) were consumed immediately after the postexercise blood sample. Results showed that the postexercise drinks had no significant (p ≥ 0.05) effect on any biomarker measured. There was a significant (p < 0.05) increase in hepcidin and interleukin-6 following intense cycling intervals in the participants. Hepcidin increased significantly (p < 0.05) from baseline (nmol·L -1 : 9.94 ± 8.93, 14.18 ± 14.90, 10.44 ± 14.62) to 3 h postexercise (nmol·L -1 : 22.27 ± 13.41, 25.44 ± 11.91, 22.57 ± 15.57) in VPRO, PRO, and PLA, respectively. Contrary to our hypothesis, the drink compositions used did not blunt the postexercise hepcidin response in highly trained athletes.

Response time of mitochondrial oxygen consumption following stepwise changes in cardiac energy demand.

PubMed

van Beek, J H; Westerhof, N

1990-01-01

We determined the speed with which mitochondrial oxygen consumption and therefore the mitochondrial ATP-synthesis adapted to changes in metabolic demand in the rabbit heart. This was done by measuring the oxygen uptake of the whole heart during a stepwise change in heart rate and correcting for the time taken by diffusion and by convective transport in the blood vessels. Data for the correction for transport time were obtained from the response of venous oxygen concentration to a stepwise change of arterial oxygen concentration. The time constant of the response of mitochondrial oxygen consumption to a step change in heart rate was found to be 4-8 s.

Dynamic regulation of erythropoiesis: A computer model of general applicability

NASA Technical Reports Server (NTRS)

Leonard, J. I.

1979-01-01

A mathematical model for the control of erythropoiesis was developed based on the balance between oxygen supply and demand at a renal oxygen detector which controls erythropoietin release and red cell production. Feedback regulation of tissue oxygen tension is accomplished by adjustments of hemoglobin levels resulting from the output of a renal-bone marrow controller. Special consideration was given to the determinants of tissue oxygenation including evaluation of the influence of blood flow, capillary diffusivity, oxygen uptake and oxygen-hemoglobin affinity. A theoretical analysis of the overall control system is presented. Computer simulations of altitude hypoxia, red cell infusion hyperoxia, and homolytic anemia demonstrate validity of the model for general human application in health and disease.

Real-time monitoring of specific oxygen uptake rates of embryonic stem cells in a microfluidic cell culture device.

PubMed

Super, Alexandre; Jaccard, Nicolas; Cardoso Marques, Marco Paulo; Macown, Rhys Jarred; Griffin, Lewis Donald; Veraitch, Farlan Singh; Szita, Nicolas

2016-09-01

Oxygen plays a key role in stem cell biology as a signaling molecule and as an indicator of cell energy metabolism. Quantification of cellular oxygen kinetics, i.e. the determination of specific oxygen uptake rates (sOURs), is routinely used to understand metabolic shifts. However current methods to determine sOUR in adherent cell cultures rely on cell sampling, which impacts on cellular phenotype. We present real-time monitoring of cell growth from phase contrast microscopy images, and of respiration using optical sensors for dissolved oxygen. Time-course data for bulk and peri-cellular oxygen concentrations obtained for Chinese hamster ovary (CHO) and mouse embryonic stem cell (mESCs) cultures successfully demonstrated this non-invasive and label-free approach. Additionally, we confirmed non-invasive detection of cellular responses to rapidly changing culture conditions by exposing the cells to mitochondrial inhibiting and uncoupling agents. For the CHO and mESCs, sOUR values between 8 and 60 amol cell(-1) s(-1) , and 5 and 35 amol cell(-1) s(-1) were obtained, respectively. These values compare favorably with literature data. The capability to monitor oxygen tensions, cell growth, and sOUR, of adherent stem cell cultures, non-invasively and in real time, will be of significant benefit for future studies in stem cell biology and stem cell-based therapies. © 2016 The Authors. Biotechnology Journal published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Tungsten Speciation in Firing Range Soils

DTIC Science & Technology

2011-01-01

R. A. A. Suurs, O . Oenema , and W. H. van Riemsdijk. 2004. Phosphorus availability for plant uptake in a phosphorus enriched noncalcareous sandy soil...heteroatom (most commonly P5+, Si4+, or B3+), M is the addenda atom (most common are molybdenum and tungsten), and O represents oxygen. The structure self...coordination to four oxygen atoms. The EXAFS spectrum of tungstate is dominated by os- cillations attributed to tungsten-oxygen (W- O ) bonding (Fig. 4), and to

Exercise training promotes cardioprotection through oxygen-sparing action in high fat-fed mice.

PubMed

Lund, J; Hafstad, A D; Boardman, N T; Rossvoll, L; Rolim, N P; Ahmed, M S; Florholmen, G; Attramadal, H; Wisløff, U; Larsen, T S; Aasum, E

2015-04-15

Although exercise training has been demonstrated to have beneficial cardiovascular effects in diabetes, the effect of exercise training on hearts from obese/diabetic models is unclear. In the present study, mice were fed a high-fat diet, which led to obesity, reduced aerobic capacity, development of mild diastolic dysfunction, and impaired glucose tolerance. Following 8 wk on high-fat diet, mice were assigned to 5 weekly high-intensity interval training (HIT) sessions (10 × 4 min at 85-90% of maximum oxygen uptake) or remained sedentary for the next 10 constitutive weeks. HIT increased maximum oxygen uptake by 13%, reduced body weight by 16%, and improved systemic glucose homeostasis. Exercise training was found to normalize diastolic function, attenuate diet-induced changes in myocardial substrate utilization, and dampen cardiac reactive oxygen species content and fibrosis. These changes were accompanied by normalization of obesity-related impairment of mechanical efficiency due to a decrease in work-independent myocardial oxygen consumption. Finally, we found HIT to reduce infarct size by 47% in ex vivo hearts subjected to ischemia-reperfusion. This study therefore demonstrated for the first time that exercise training mediates cardioprotection following ischemia in diet-induced obese mice and that this was associated with oxygen-sparing effects. These findings highlight the importance of optimal myocardial energetics during ischemic stress. Copyright © 2015 the American Physiological Society.

Gill remodelling during terrestrial acclimation reduces aquatic respiratory function of the amphibious fish Kryptolebias marmoratus.

PubMed

Turko, Andy J; Cooper, Chris A; Wright, Patricia A

2012-11-15

The skin-breathing amphibious fish Kryptolebias marmoratus experiences rapid environmental changes when moving between water- and air-breathing, but remodelling of respiratory morphology is slower (~1 week). We tested the hypotheses that (1) there is a trade-off in respiratory function of gills displaying aquatic versus terrestrial morphologies and (2) rapidly increased gill ventilation is a mechanism to compensate for reduced aquatic respiratory function. Gill surface area, which varied inversely to the height of the interlamellar cell mass, was increased by acclimating fish for 1 week to air or low ion water, or decreased by acclimating fish for 1 week to hypoxia (~20% dissolved oxygen saturation). Fish were subsequently challenged with acute hypoxia, and gill ventilation or oxygen uptake was measured. Fish with reduced gill surface area increased ventilation at higher dissolved oxygen levels, showed an increased critical partial pressure of oxygen and suffered impaired recovery compared with brackish water control fish. These results indicate that hyperventilation, a rapid compensatory mechanism, was only able to maintain oxygen uptake during moderate hypoxia in fish that had remodelled their gills for land. Thus, fish moving between aquatic and terrestrial habitats may benefit from cutaneously breathing oxygen-rich air, but upon return to water must compensate for a less efficient branchial morphology (mild hypoxia) or suffer impaired respiratory function (severe hypoxia).

Mechanisms That Modulate Peripheral Oxygen Delivery during Exercise in Heart Failure.

PubMed

Kisaka, Tomohiko; Stringer, William W; Koike, Akira; Agostoni, Piergiuseppe; Wasserman, Karlman

2017-07-01

Oxygen uptake ([Formula: see text]o 2 ) measured at the mouth, which is equal to the cardiac output (CO) times the arterial-venous oxygen content difference [C(a-v)O 2 ], increases more than 10- to 20-fold in normal subjects during exercise. To achieve this substantial increase in oxygen uptake [[Formula: see text]o 2  = CO × C(a-v)O 2 ] both CO and the arterial-venous difference must simultaneously increase. Although this occurs in normal subjects, patients with heart failure cannot achieve significant increases in cardiac output and must rely primarily on changes in the arterial-venous difference to increase [Formula: see text]o 2 during exercise. Inadequate oxygen delivery to the tissue during exercise in heart failure results in tissue anaerobiosis, lactic acid accumulation, and reduction in exercise tolerance. H + is an important regulatory and feedback mechanism to facilitate additional oxygen delivery to the tissue (Bohr effect) and further aerobic production of ATP when tissue anaerobic metabolism increases the production of lactate (anaerobic threshold). This H + production in the muscle capillary promotes the continued unloading of oxygen (oxyhemoglobin desaturation) while maintaining the muscle capillary Po 2 (Fick principle) at a sufficient level to facilitate aerobic metabolism and overcome the diffusion barriers from capillary to mitochondria ("critical capillary Po 2 ," 15-20 mm Hg). This mechanism is especially important during exercise in heart failure where cardiac output increase is severely constrained. Several compensatory mechanisms facilitate peripheral oxygen delivery during exercise in both normal persons and patients with heart failure.

Singlet oxygen in the coupled photochemical and biochemical oxidation of dissolved organic matter.

PubMed

Cory, Rose M; McNeill, Kristopher; Cotner, James P; Amado, Andre; Purcell, Jeremiah M; Marshall, Alan G

2010-05-15

Dissolved organic matter (DOM) is a significant (>700 Pg) global C pool. Transport of terrestrial DOM to the inland waters and coastal zones represents the largest flux of reduced C from land to water (215 Tg yr(-1)) (Meybeck, M. Am. J. Sci. 1983, 282, 401-450). Oxidation of DOM by interdependent photochemical and biochemical processes largely controls the fate of DOM entering surface waters. Reactive oxygen species (ROS) have been hypothesized to play a significant role in the photooxidation of DOM, because they may oxidize the fraction of DOM that is inaccessible to direct photochemical degradation by sunlight. We followed the effects of photochemically produced singlet oxygen ((1)O(2)) on DOM by mass spectrometry with (18)O-labeled oxygen, to understand how (1)O(2)-mediated transformations of DOM may lead to altered DOM bioavailability. The photochemical oxygen uptake by DOM attributed to (1)O(2) increased with DOM concentration, yet it remained a minority contributor to photochemical oxygen uptake even at very high DOM concentrations. When DOM samples were exposed to (1)O(2)-generating conditions (Rose Bengal and visible light), increases were observed in DOM constituents with higher oxygen content and release of H(2)O(2) was detected. Differential effects of H(2)O(2) and (1)O(2)-treated DOM showed that (1)O(2)-treated DOM led to slower bacterial growth rates relative to unmodified DOM. Results of this study suggested that the net effect of the reactions between singlet oxygen and DOM may be production of partially oxidized substrates with correspondingly lower potential biological energy yield.

Phytoplankton productivity, respiration, and nutrient uptake and regeneration in the Potomac River, August 1977 - August 1978

USGS Publications Warehouse

Cole, B.E.; Harmon, D.D.

1981-01-01

Rates of phytoplankton productivity, respiration, and nutrient uptake and regeneration are presented. These observations were made on the Potomac River estuary (POTE) during four cruises between August 1977 and August 1978. Four experimental methods were used: carbon uptake using carbon-14, carbon uptake and respiration by a pH method, productivity and respiration by the dissolved oxygen method, and nutrient (NH4+, NO3-, NO2-, PO4=, and SiO2=) uptake and regeneration by colorimetry. The experiments were made at sites representative of conditions in four principal reaches of the tidal Potomac River estuary: near the mouth, seaward of the summer nutrient and phytoplankton maximum, near the region of maximum phytoplankton standing stock , and near the maximum anthropogenic nutrient source. (USGS)

Biological Oxygen Demand in Soils and Litters

NASA Astrophysics Data System (ADS)

Smagin, A. V.; Smagina, M. V.; Sadovnikova, N. B.

2018-03-01

Biological oxygen demand (BOD) in mineral and organic horizons of soddy-podzolic soils in the forest-park belt of Moscow as an indicator of their microbial respiration and potential biodestruction function has been studied. The BOD of soil samples has been estimated with a portable electrochemical analyzer after incubation in closed flasks under optimum hydrothermal conditions. A universal gradation scale of this parameter from very low (<2 g O2/(m3 h)) to extremely high (>140 g O2/(m3 h)) has been proposed for mineral and organic horizons of soil. A physically substantiated model has been developed for the vertical distribution of BOD in the soil, which combines the diffusion transport of oxygen from the atmosphere and its biogenic uptake in the soil by the first-order reaction. An analytical solution of the model in the stationary state has been obtained; from it, the soil oxygen diffusivity and the kinetic constants of O2 uptake have been estimated, and the profile-integrated total BOD value has been calculated (0.4-1.8 g O2/(m2 h)), which is theoretically identical to the potential oxygen flux from the soil surface due to soil respiration. All model parameters reflect the recreation load on the soil cover by the decrease in their values against the control.

Effects of Hemopure on maximal oxygen uptake and endurance performance in healthy humans.

PubMed

Ashenden, M J; Schumacher, Y O; Sharpe, K; Varlet-Marie, E; Audran, M

2007-05-01

Haemoglobin-based oxygen carriers (HBOCs) such as Hemopure are touted as a tenable substitute for red blood cells and therefore potential doping agents, although the mechanisms of oxygen transport of HBOCs are incompletely understood. We investigated whether infusion of Hemopure increased maximal oxygen uptake (V.O 2max) and endurance performance in healthy subjects. Twelve male subjects performed two 4-minute submaximal exercise bouts equivalent to 60 % and 75 % of V.O (2max) on a cycle ergometer, followed by a ramped incremental protocol to elicit V.O (2max). A crossover design tested the effect of infusing either 30 g (6 subjects) or 45 g (6 subjects) of Hemopure versus a placebo. Under our study conditions, Hemopure did not increase V.O (2max) nor endurance performance. However, the infusion of Hemopure caused a decrease in heart rate of approximately 10 bpm (p=0.009) and an average increase in mean ( approximately 7 mmHg) and diastolic blood pressure ( approximately 8 mmHg) (p=0.046) at submaximal and maximal exercise intensities. Infusion of Hemopure did not bestow the same physiological advantages generally associated with infusion of red blood cells. It is conceivable that under exercise conditions, the hypertensive effects of Hemopure counter the performance-enhancing effect of improved blood oxygen carrying capacity.

Gill structural change in response to turbidity has no effect on the oxygen uptake of a juvenile sparid fish.

PubMed

Cumming, H; Herbert, N A

2016-01-01

Turbidity as a result of increased suspended sediments in coastal waters is an environmental stress of worldwide concern. Recent research on fish suggests that detrimental changes to gill structure can occur in turbid waters, with speculation that these alterations diminish fitness variables, such as growth and development, by negatively impacting the O 2 uptake capacity (respiration) of fish. Specifically to address this unknown, the impact of turbid water on the gill structure, somatic growth rate and O 2 uptake rates of a juvenile sparid species ( Pagrus auratus ) was addressed following exposure to five different turbidity treatments (<10, 20, 40, 60 or 80 nephelometric turbidity units) for 30 days. Significant gill structural change was apparent with a progressive increase in turbidity and was quantified as a reduction in lamellar density, as well as an increase in basal hyperplasia, epithelial lifting and increased oxygen diffusion distance across the lamellae. The weight of control fish did not change throughout the experiment, but all fish exposed to turbid waters lost weight, and weight loss increased with nephelometric turbidity units, confirming that long-term turbidity exposure is detrimental to growth productivity. The growth of fish could be impacted in a variety of ways, but the specific hypothesis that structural alteration of the gills impairs O 2 uptake across the gills and limits growth fitness was not supported because there was no measurable difference in the standard metabolic rate, maximal metabolic rate, aerobic metabolic scope or critical oxygen saturation limit of fish measured in clear water after 30 days of exposure. Although impaired O 2 uptake as a result of structurally adjusted gills is unlikely to be the cause of poor fish growth, the exact mechanism by which growth productivity is affected in turbid conditions remains unclear and warrants further investigation.

Gill structural change in response to turbidity has no effect on the oxygen uptake of a juvenile sparid fish

PubMed Central

Cumming, H.; Herbert, N. A.

2016-01-01

Turbidity as a result of increased suspended sediments in coastal waters is an environmental stress of worldwide concern. Recent research on fish suggests that detrimental changes to gill structure can occur in turbid waters, with speculation that these alterations diminish fitness variables, such as growth and development, by negatively impacting the O2 uptake capacity (respiration) of fish. Specifically to address this unknown, the impact of turbid water on the gill structure, somatic growth rate and O2 uptake rates of a juvenile sparid species (Pagrus auratus) was addressed following exposure to five different turbidity treatments (<10, 20, 40, 60 or 80 nephelometric turbidity units) for 30 days. Significant gill structural change was apparent with a progressive increase in turbidity and was quantified as a reduction in lamellar density, as well as an increase in basal hyperplasia, epithelial lifting and increased oxygen diffusion distance across the lamellae. The weight of control fish did not change throughout the experiment, but all fish exposed to turbid waters lost weight, and weight loss increased with nephelometric turbidity units, confirming that long-term turbidity exposure is detrimental to growth productivity. The growth of fish could be impacted in a variety of ways, but the specific hypothesis that structural alteration of the gills impairs O2 uptake across the gills and limits growth fitness was not supported because there was no measurable difference in the standard metabolic rate, maximal metabolic rate, aerobic metabolic scope or critical oxygen saturation limit of fish measured in clear water after 30 days of exposure. Although impaired O2 uptake as a result of structurally adjusted gills is unlikely to be the cause of poor fish growth, the exact mechanism by which growth productivity is affected in turbid conditions remains unclear and warrants further investigation. PMID:27766155

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

PubMed

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

2018-04-27

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

Poor Aeration Curtails Slash Pine Root Growth and Nutrient Uptake

Treesearch

Eugene Shoulders

1976-01-01

Slash pine may absorb nutrients and water best in spring and early summer because soil moisture, soil aeration, and temperature are apparently optimum at this time. One-year-old slash pine seedlings maintained at a high oxygen level grew about 1% times as many roots as were produced at a low oxygen level. No other environmental conditions significantly influenced root...

Cystine uptake through the cystine/glutamate antiporter xCT triggers glioblastoma cell death under glucose deprivation.

PubMed

Goji, Takeo; Takahara, Kazuhiko; Negishi, Manabu; Katoh, Hironori

2017-12-01

Oncogenic signaling in cancer cells alters glucose uptake and utilization to supply sufficient energy and biosynthetic intermediates for survival and sustained proliferation. Oncogenic signaling also prevents oxidative stress and cell death caused by increased production of reactive oxygen species. However, elevated glucose metabolism in cancer cells, especially in glioblastoma, results in the cells becoming sensitive to glucose deprivation ( i.e. in high glucose dependence), which rapidly induces cell death. However, the precise mechanism of this type of cell death remains unknown. Here, we report that glucose deprivation alone does not trigger glioblastoma cell death. We found that, for cell death to occur in glucose-deprived glioblastoma cells, cystine and glutamine also need to be present in culture media. We observed that cystine uptake through the cystine/glutamate antiporter xCT under glucose deprivation rapidly induces NADPH depletion, reactive oxygen species accumulation, and cell death. We conclude that although cystine uptake is crucial for production of antioxidant glutathione in cancer cells its transport through xCT also induces oxidative stress and cell death in glucose-deprived glioblastoma cells. Combining inhibitors targeting cancer-specific glucose metabolism with cystine and glutamine treatment may offer a therapeutic approach for glioblastoma tumors exhibiting high xCT expression. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Oxygen consumption of elite distance runners on an anti-gravity treadmill®.

PubMed

McNeill, David K P; Kline, John R; de Heer, Hendrick D; Coast, J Richard

2015-06-01

Lower body positive pressure (LBPP), or 'anti-gravity' treadmills® have become increasingly popular among elite distance runners. However, to date, few studies have assessed the effect of body weight support (BWS) on the metabolic cost of running among elite runners. This study evaluated how BWS influenced the relationship between velocity and metabolic cost among 6 elite male distance runners. Participants ran three- 16 minute tests consisting of 4 stages of 4 minutes at 8, 7, 6 and 5 min·mile(-1) pace (3.35, 3.84, 4.47 and 5.36 m·s(-1)), while maintaining an aerobic effort (Respiratory Exchange Ratio ≤1.00). One test was run on a regular treadmill, one on an anti-gravity treadmill with 40% BWS and one with 20% BWS being provided. Expired gas data were collected and regression equations used to determine and compare slopes. Significant decreases in oxygen uptake (V̇O2) were found with each increase in BWS (p < 0.001). At 20% BWS, the average decrease in net VO2 was greater than proportional (34%), while at 40% BWS, the average net reduction in VO2 was close to proportional (38%). Across velocities, the slope of the relationship between VO2 and velocity (ΔV̇O2/Δv) was steeper with less support. The slopes at both the 20% and 40% BWS conditions were similar, especially when compared to the regular treadmill. Variability in VO2 between athletes was much greater on the LBPP treadmill and was greater with increased levels of BWS. In this study we evaluated the effect of body weight support on V̇O2 among elite distance runners. We have shown that oxygen uptake decreased with support, but not in direct proportion to that support. Further, because of the high variability in oxygen uptake between athletes on the LBPP treadmill, prediction equations may not be reliable and other indicators (heart rate, perceived exertion or directly measured oxygen uptake) should be used to guide training intensity when training on the LBPP treadmill. Key pointsWith increasing amounts of body weight-support (BWS), the slope of the relationship between velocity and oxygen consumption (ΔVO2/Δv) decreases significantly. This means the change in oxygen consumption (VO2) is significantly smaller over a given change in velocity at higher amounts of BWS.There is a non-linear decrease in VO2 with increasing BWS. As such, with each increment in the amount of BWS provided, the reduction in VO2 becomes increasingly smaller.This paper provides first of its kind data on the effects of BWS on the cost of running among highly trained, elite runners. The outcomes of this study are in line with previous findings among non-elite runners.

A Novel Anoxic Pathway for Urea and Cyanate in Marine Oxygen Deficient Zones Revealed by Combined Microbiological and Biogeochemical Tools

NASA Astrophysics Data System (ADS)

Widner, B.; Fuchsman, C. A.; Babbin, A. R.; Ji, Q.; Mulholland, M. R.

2016-02-01

Urea and cyanate are reduced nitrogen compounds that can serve as nitrogen and carbon sources for marine microbes, and cyanate forms from decomposition of urea. Some marine bacteria, including cyanobacteria, possess genes encoding an ABC-type cyanate transporter and an intracellular cyanate hydratase, and genes for urea uptake and assimilation are widespread. To investigate cyanate distribution and availability in the ocean, we recently developed a nanomolar cyanate assay specific to seawater. In an oxygenated water column, urea and cyanate concentrations are generally low in surface waters and exhibit a concentration maximum near the base of the euphotic zone likely due to production from organic matter degradation. Below the euphotic zone, urea and cyanate concentrations decrease, likely due to oxidation reactions. It has been suggested that simple organic nitrogen compounds may support anaerobic ammonium oxidation (anammox) in oxygen deficient zones (ODZs). We mapped urea and cyanate distributions and used stable isotope-labeled urea and cyanate to measure their potential support of anammox and their uptake within the Eastern Tropical North and South Pacific ODZs. We also employed metagenomic techniques to determine the abundance and distribution of genes for the uptake and assimilation of urea and cyanate. The combined data indicate that, in ODZs, urea is used primarily as a nitrogen source while cyanate is used as both a nitrogen source and to generate energy.

The physiological and biomechanical differences between double poling and G3 skating in world class cross-country skiers.

PubMed

Sandbakk, Øyvind; Leirdal, Stig; Ettema, Gertjan

2015-03-01

The current study compared differences in cycle characteristics, energy expenditure and peak speed between double poling (DP) and G3 skating. Eight world class male sprint skiers performed a 5-min submaximal test at 16 km h(-1) and an incremental test to exhaustion at a 5% incline during treadmill roller skiing with two different techniques: DP where all propulsion comes from poling, and G3 skating where leg skating is added to each double poling movement. Video analyses determined cycle characteristics; respiratory parameters and blood lactate concentration determined the physiological responses. G3 skating resulted in 16% longer cycle lengths at 16% lower cycle rates, whereas oxygen uptake was independent of technique during submaximal roller skiing. The corresponding advantages for G3 skating during maximal roller skiing were reflected in 14% higher speed, 30% longer cycle length at 16% lower cycle rate and 11% higher peak oxygen uptake (all p < 0.05). Compared to DP approximately 14% higher speed was achieved when leg push-offs were added in G3 skating. This was done by major increases in cycle lengths at slightly lower cycle rates and a higher aerobic energy delivery. However, the oxygen uptake for a given submaximal speed was not affected by technique although higher cycle rate was used in DP.

Effect of 400 ml blood loss on adaptation of certain functions of the organism to exercise.

PubMed

Markiewicz, K; Cholewa, M; Górski, L; Jaszczuk, J; Chmura, J; Bartniczak, Z

1981-01-01

Eighteen men aged 19-23 years, volunteer blood donors, donated 400 ml of blood. Twenty-four hours before donation, one hour and 24 hours after it they performed a 10-minute exercise on Monark cycle ergometer at workloads raising the heart rate to 170/min. During the exercise the oxygen uptake (VO2), carbon dioxide elimination (VCO2), respiratory quotient (RQ), oxygen uptake to maximal oxygen uptake ratio (VO2/VO2 max), heart rate (HR) and systolic and diastolic arterial blood pressure (Ps and Pd) were determined. The obtained results were compared with the values of haemoglobin concentration and erythrocyte count. One hour after blood donation raised values of HR and Pd were obtained (p less than 0.05) with decreased Ps (p less than 0.05) and VO2 (p less than 0.05). Twenty-four hours after blood loss these parameters were not different from the initial ones (p less than 0.05). Submaximal exercise performed 1 hour after blood loss produced a significantly greater increase of the heart rate than this exercise performed before blood loss. The values of VO2, VCO2, and VO2/VO2 max were slightly lower and those of RQ and HRXPs slightly higher than during control exercise (p less than 0.05). Exercise performed 24 hours after blood loss caused identical changes in these parameters as during control tests.

Photoluminescent Gold Nanoclusters in Cancer Cells: Cellular Uptake, Toxicity, and Generation of Reactive Oxygen Species.

PubMed

Matulionyte, Marija; Dapkute, Dominyka; Budenaite, Laima; Jarockyte, Greta; Rotomskis, Ricardas

2017-02-10

In recent years, photoluminescent gold nanoclusters have attracted considerable interest in both fundamental biomedical research and practical applications. Due to their ultrasmall size, unique molecule-like optical properties, and facile synthesis gold nanoclusters have been considered very promising photoluminescent agents for biosensing, bioimaging, and targeted therapy. Yet, interaction of such ultra-small nanoclusters with cells and other biological objects remains poorly understood. Therefore, the assessment of the biocompatibility and potential toxicity of gold nanoclusters is of major importance before their clinical application. In this study, the cellular uptake, cytotoxicity, and intracellular generation of reactive oxygen species (ROS) of bovine serum albumin-encapsulated (BSA-Au NCs) and 2-(N-morpholino) ethanesulfonic acid (MES)capped photoluminescent gold nanoclusters (Au-MES NCs) were investigated. The results showed that BSA-Au NCs accumulate in cells in a similar manner as BSA alone, indicating an endocytotic uptake mechanism while ultrasmall Au-MES NCs were distributed homogeneously throughout the whole cell volume including cell nucleus. The cytotoxicity of BSA-Au NCs was negligible, demonstrating good biocompatibility of such BSA-protected Au NCs. In contrast, possibly due to ultrasmall size and thin coating layer, Au-MES NCs exhibited exposure time-dependent high cytotoxicity and higher reactivity which led to highly increased generation of reactive oxygen species. The results demonstrate the importance of the coating layer to biocompatibility and toxicity of ultrasmall photoluminescent gold nanoclusters.

Physiological effects of a new racing suit for elite cross country skiers.

PubMed

Sperlich, B; Holmberg, H C

2011-12-01

The aim of this paper was to investigate the influence of the new cross country racing suit, designed for the Olympic Winter Games in Vancouver 2010, on cardio-respiratory, thermoregulatory and perceptual responses. Six elite cross country skiers (29±6 years, peak oxygen uptake 73.2±6.9 mL·min-1·kg-1) performed two exercise bouts wearing either the 2009 or the 2010 racing suit. Bouts consisted of incremental testing on roller skis (12 km·h-1 at 5° inclination; 11 km·h-1 at 6° inclination and 12 km·h-1at 8° inclination for six minutes). During increasing intensities, significantly lower values were found for oxygen uptake, minute ventilation, RER and heart rate when wearing the new suit compared to the old one (P<0.05; effect sizes: 0.21-4.00). Core temperature was lower with the new suit during steps 2 and 3 (P<0.05, effect size: 1.22-1.27). Also, mean skin temperature was lower during the last increment (P<0.05, effect size: 0.87). The new 2010 racing suit, developed specifically for the Olympic Winter Games in Vancouver 2010, demonstrated lower values for oxygen uptake, minute ventilation, heart rate, skin and core temperature, ratings of thermal and sweat sensation when compared to the 2009 racing suit.

Photoluminescent Gold Nanoclusters in Cancer Cells: Cellular Uptake, Toxicity, and Generation of Reactive Oxygen Species

PubMed Central

Matulionyte, Marija; Dapkute, Dominyka; Budenaite, Laima; Jarockyte, Greta; Rotomskis, Ricardas

2017-01-01

In recent years, photoluminescent gold nanoclusters have attracted considerable interest in both fundamental biomedical research and practical applications. Due to their ultrasmall size, unique molecule-like optical properties, and facile synthesis gold nanoclusters have been considered very promising photoluminescent agents for biosensing, bioimaging, and targeted therapy. Yet, interaction of such ultra-small nanoclusters with cells and other biological objects remains poorly understood. Therefore, the assessment of the biocompatibility and potential toxicity of gold nanoclusters is of major importance before their clinical application. In this study, the cellular uptake, cytotoxicity, and intracellular generation of reactive oxygen species (ROS) of bovine serum albumin-encapsulated (BSA-Au NCs) and 2-(N-morpholino) ethanesulfonic acid (MES)-capped photoluminescent gold nanoclusters (Au-MES NCs) were investigated. The results showed that BSA-Au NCs accumulate in cells in a similar manner as BSA alone, indicating an endocytotic uptake mechanism while ultrasmall Au-MES NCs were distributed homogeneously throughout the whole cell volume including cell nucleus. The cytotoxicity of BSA-Au NCs was negligible, demonstrating good biocompatibility of such BSA-protected Au NCs. In contrast, possibly due to ultrasmall size and thin coating layer, Au-MES NCs exhibited exposure time-dependent high cytotoxicity and higher reactivity which led to highly increased generation of reactive oxygen species. The results demonstrate the importance of the coating layer to biocompatibility and toxicity of ultrasmall photoluminescent gold nanoclusters. PMID:28208642

The Maximal Oxygen Uptake Verification Phase: a Light at the End of the Tunnel?

PubMed

Schaun, Gustavo Z

2017-12-08

Commonly performed during an incremental test to exhaustion, maximal oxygen uptake (V̇O 2max ) assessment has become a recurring practice in clinical and experimental settings. To validate the test, several criteria were proposed. In this context, the plateau in oxygen uptake (V̇O 2 ) is inconsistent in its frequency, reducing its usefulness as a robust method to determine "true" V̇O 2max . Moreover, secondary criteria previously suggested, such as expiratory exchange ratios or percentages of maximal heart rate, are highly dependent on protocol design and often are achieved at V̇O 2 percentages well below V̇O 2max . Thus, an alternative method termed verification phase was proposed. Currently, it is clear that the verification phase can be a practical and sensitive method to confirm V̇O 2max ; however, procedures to conduct it are not standardized across the literature and no previous research tried to summarize how it has been employed. Therefore, in this review the knowledge on the verification phase was updated, while suggestions on how it can be performed (e.g. intensity, duration, recovery) were provided according to population and protocol design. Future studies should focus to identify a verification protocol feasible for different populations and to compare square-wave and multistage verification phases. Additionally, studies assessing verification phases in different patient populations are still warranted.

Metabolic Cost of Experimental Exercises

NASA Technical Reports Server (NTRS)

Webb, James T.; Gernhardt, Michael L.

2009-01-01

Although the type and duration of activity during decompression was well documented, the metabolic cost of 1665 subject-exposures with 8 activity profiles from 17 altitude decompression sickness (DCS) protocols at Brooks City-Base, TX from 1983-2005 was not determined. Female and male human volunteers (30 planned, 4 completed) performed activity profiles matching those 8 activity profiles at ground level with continuous monitoring of metabolic cost. A Cosmed K4b2 Cardio Pulmonary Exercise Testing device was used to measure oxygen uptake (VO2) during the profiles. The results show levels of metabolic cost to the females for the profiles tested varied from 4.3 to 25.5 ml/kg/min and from 3.0 to 12.0 ml/kg/min to the males. The increase in VO2 from seated rest to the most strenuous of the 8 activity profiles was 3.6-fold for the females and 2.8-fold for the males. These preliminary data on 4 subjects indicate close agreement of oxygen uptake for activity performed during many subject-exposures as published earlier. The relatively low average oxygen uptake required to perform the most strenuous activity may imply the need for adjustment of modeling efforts using metabolic cost as a risk factor. Better definition of metabolic cost during exposure to altitude, a critical factor in DCS risk, may allow refinement of DCS prediction models.

Growth, biomass allocation and nutrient use efficiency in Cladium jamaicense and Typha domingensis as affected by phosphorus and oxygen availability

USGS Publications Warehouse

Lorenzen, B.; Brix, H.; Mendelssohn, I.A.; McKee, K.L.; Miao, S.L.

2001-01-01

The effects of phosphorus (P) and oxygen availability on growth, biomass allocation and nutrient use efficiency in Cladium jamaicense Crantz and Typha domingensis Pers. were studied in a growth facility equipped with steady-state hydroponic rhizotrons. The treatments included four P concentrations (10, 40, 80 and 500 ??g I-1) and two oxygen concentration (8.0 and <0.5 mg O2 I-1) in the culture solutions. In Cladium, no clear relationship was found between P availability and growth rate (19-37 mg g-1 d-1), the above to below ground biomass ratio (A/B) (mean = 4.6), or nitrogen use efficiency (NUE) (mean = 72 g dry weight g-1 N). However, the ratio between root supported tissue (leaves, rhizomes and ramets) and root biomass (S/R) (5.6-8) increased with P availability. In contrast, the growth rate (48-89 mg g-1 d-1) and the biomass ratios A/B (2.4-6.1) and S/R (5.4-10.3) of Typha increased with P availability, while NUE (71-30 g dry weight g-1 N) decreased. The proportion of root laterals was similar in the two species, but Typha had thinner root laterals (diameter = 186 ??m) than Cladium (diameter = 438 ??m) indicating a larger root surface area in Typha. The two species had a similar P use efficiency (PUE) at 10 ??g PI-1 (mean = 1134 g dry weight g-1 P) and at 40 and 80 ??g PI-1 (mean = 482 dry weight g-1 P) but the N/P ratio indicated imbalances in nutrient uptake at a higher P concentration (40 ??g PI-1) in Typha than in Cladium (10 ??g PI-1). The two species had similar root specific P accumulation rate at the two lowest P levels, whereas Typha had 3-13-fold higher P uptake rates at the two highest P levels, indicating a higher nutrient uptake capacity in Typha. The experimental oxygen concentration in the rhizosphere had only limited effect on the growth of the two species and had little effect on biomass partitioning and nutrient use efficiency. The aerenchyma in these species was probably sufficient to maintain adequate root oxygenation under partially oxygen depleted conditions. Cladium had characteristics typical for plants from nutrient poor habitats, which included slow growth rate, low capacity for P uptake and relatively inflexible biomass partitioning in response to increased P availability. In contrast, Typha demonstrated a high degree of flexibility in growth, biomass partitioning, and nutrient accumulation to P availability, similar to species from nutrient rich habitats. Although the N/P ratio indicated that Typha was more nutrient stressed at the low P levels, Typha had a higher capacity for P uptake and was more competitive than Cladium at the applied P concentrations. ?? 2001 Elsevier Science B.V.

Evolution of Air Breathing: Oxygen Homeostasis and the Transitions from Water to Land and Sky

PubMed Central

Hsia, Connie C. W.; Schmitz, Anke; Lambertz, Markus; Perry, Steven F.; Maina, John N.

2014-01-01

Life originated in anoxia, but many organisms came to depend upon oxygen for survival, independently evolving diverse respiratory systems for acquiring oxygen from the environment. Ambient oxygen tension (PO2) fluctuated through the ages in correlation with biodiversity and body size, enabling organisms to migrate from water to land and air and sometimes in the opposite direction. Habitat expansion compels the use of different gas exchangers, for example, skin, gills, tracheae, lungs, and their intermediate stages, that may coexist within the same species; coexistence may be temporally disjunct (e.g., larval gills vs. adult lungs) or simultaneous (e.g., skin, gills, and lungs in some salamanders). Disparate systems exhibit similar directions of adaptation: toward larger diffusion interfaces, thinner barriers, finer dynamic regulation, and reduced cost of breathing. Efficient respiratory gas exchange, coupled to downstream convective and diffusive resistances, comprise the “oxygen cascade”—step-down of PO2 that balances supply against toxicity. Here, we review the origin of oxygen homeostasis, a primal selection factor for all respiratory systems, which in turn function as gatekeepers of the cascade. Within an organism's lifespan, the respiratory apparatus adapts in various ways to upregulate oxygen uptake in hypoxia and restrict uptake in hyperoxia. In an evolutionary context, certain species also become adapted to environmental conditions or habitual organismic demands. We, therefore, survey the comparative anatomy and physiology of respiratory systems from invertebrates to vertebrates, water to air breathers, and terrestrial to aerial inhabitants. Through the evolutionary directions and variety of gas exchangers, their shared features and individual compromises may be appreciated. PMID:23720333

Evolution of air breathing: oxygen homeostasis and the transitions from water to land and sky.

PubMed

Hsia, Connie C W; Schmitz, Anke; Lambertz, Markus; Perry, Steven F; Maina, John N

2013-04-01

Life originated in anoxia, but many organisms came to depend upon oxygen for survival, independently evolving diverse respiratory systems for acquiring oxygen from the environment. Ambient oxygen tension (PO2) fluctuated through the ages in correlation with biodiversity and body size, enabling organisms to migrate from water to land and air and sometimes in the opposite direction. Habitat expansion compels the use of different gas exchangers, for example, skin, gills, tracheae, lungs, and their intermediate stages, that may coexist within the same species; coexistence may be temporally disjunct (e.g., larval gills vs. adult lungs) or simultaneous (e.g., skin, gills, and lungs in some salamanders). Disparate systems exhibit similar directions of adaptation: toward larger diffusion interfaces, thinner barriers, finer dynamic regulation, and reduced cost of breathing. Efficient respiratory gas exchange, coupled to downstream convective and diffusive resistances, comprise the "oxygen cascade"-step-down of PO2 that balances supply against toxicity. Here, we review the origin of oxygen homeostasis, a primal selection factor for all respiratory systems, which in turn function as gatekeepers of the cascade. Within an organism's lifespan, the respiratory apparatus adapts in various ways to upregulate oxygen uptake in hypoxia and restrict uptake in hyperoxia. In an evolutionary context, certain species also become adapted to environmental conditions or habitual organismic demands. We, therefore, survey the comparative anatomy and physiology of respiratory systems from invertebrates to vertebrates, water to air breathers, and terrestrial to aerial inhabitants. Through the evolutionary directions and variety of gas exchangers, their shared features and individual compromises may be appreciated.

Correlation between the sorption of dissolved oxygen onto chitosan and its antimicrobial activity against Esherichia coli.

PubMed

Gylienė, Ona; Servienė, Elena; Vepštaitė, Iglė; Binkienė, Rima; Baranauskas, Mykolas; Lukša, Juliana

2015-10-20

The ability of chitosan to adsorb dissolved oxygen from solution depends on its physical shape and is related to the surface area. Depending on conditions chitosan is capable of adsorbing or releasing oxygen. Chitosan, modificated by the substances possessing antimicrobial activity, such as succinic acid, Pd(II) ions, metallic Pd or Ag, distinctly increases the ability to adsorb the dissolved oxygen. The additional treatment of chitosan with air oxygen or electrochemically produced oxygen also increases the uptake of dissolved oxygen by chitosan. A strong correlation between the amount of oxygen adsorbed onto chitosan and its antimicrobial activity against Esherichia coli has been observed. This finding suggests that one of the sources of antimicrobial activity of chitosan is the ability to sorb dissolved oxygen, along with other well-known factors such as physical state and chemical composition. Copyright © 2015 Elsevier Ltd. All rights reserved.

The importance of perivitelline fluid convection to oxygen uptake of Pseudophryne bibronii eggs.

PubMed

Mueller, Casey A; Seymour, Roger S

2011-01-01

The ciliated epithelium of amphibian embryos produces a current within the perivitelline fluid of the egg that is important in the convective transfer of oxygen to the embryo's surface. The effects of convection on oxygen uptake and the immediate oxygen environment of the embryo were investigated in Pseudophryne bibronii. Gelatin was injected into the eggs, setting the perivitelline fluid and preventing convective flow. Oxygen consumption rate (M(.)o₂) and the oxygen partial pressure (Po₂) of the perivitelline fluid were measured in eggs with and without this treatment. M(.)o₂ decreased in eggs without convection at Gosner stages 17-19 under normoxia. The lack of convection also shifted embryos from regulators to conformers as environmental Po₂ decreased. A strong Po₂ gradient formed within the eggs when convection was absent, demonstrating that the loss of convection is equivalent to decreasing the inner radius of the capsule, an important factor in gas exchange, by 25%. M(.)o₂ also declined in stage 26-27 embryos without cilia-driven convection, although not to the extent of younger stages, because of muscular movements and a greater skin surface area in direct contact with the inner capsule wall. This study demonstrates the importance of convective flow within the perivitelline fluid to gas exchange. Convection is especially important in the middle of embryonic development, when the perivitelline space has formed, creating a barrier to gas exchange, but the embryos have yet to develop muscular movements or have a large surface area exposed directly to the jelly capsule.

Physiological correlates of symbiont migration during bleaching of two octocoral species.

PubMed

Netherton, Sarah E; Scheer, Daniele M; Morrison, Patrick R; Parrin, Austin P; Blackstone, Neil W

2014-05-01

Perturbed colonies of Phenganax parrini and Sarcothelia sp. exhibit migration of symbionts of Symbiodinium spp. into the stolons. Densitometry and visual inspection indicated that polyps bleached while stolons did not. When migration was triggered by temperature, light and confinement, colonies of Sarcothelia sp. decreased rates of oxygen formation in the light (due to the effects of perturbation on photosynthesis and respiration) and increased rates of oxygen uptake in the dark (due to the effects of perturbation on respiration alone). Colonies of P. parrini, by contrast, showed no significant changes in either aspect of oxygen metabolism. When migration was triggered by light and confinement, colonies of Sarcothelia sp. showed decreased rates of oxygen formation in the light and increased rates of oxygen uptake in the dark, while colonies of P. parrini maintained the former and increased the latter. During symbiont migration into their stolons, colonies of both species showed dramatic increases in reactive oxygen species (ROS), as visualized with a fluorescent probe, with stolons of Sarcothelia sp. exhibiting a nearly immediate increase of ROS. Differences in symbiont type may explain the greater sensitivity of colonies of Sarcothelia sp. Using fluorescent probes, direct measurements of migrating symbionts in the stolons of Sarcothelia sp. showed higher levels of reactive nitrogen species and lower levels of ROS than the surrounding host tissue. As measured by native fluorescence, levels of NAD(P)H in the stolons were unaffected by perturbation. Symbiont migration thus correlates with dramatic physiological changes and may serve as a marker for coral condition.

Increased red cell 2,3-diphosphoglycerate levels in haemodialysis patients treated with erythropoietin.

PubMed

Horina, J H; Schwaberger, G; Brussee, H; Sauseng-Fellegger, G; Holzer, H; Krejs, G J

1993-01-01

The efficacy of recombinant human erythropoietin (rHuEpo) for the treatment of renal anaemia is well established. To assess the effect of rHuEpo treatment on physical performance we evaluated physical working capacity, oxygen uptake and red cell 2,3-diphosphoglycerate (DPG) values at rest and during and after exercise on a bicycle spiroergometer in eight chronically haemodialysed patients. Follow-up examination was carried out after a mean of 14 weeks (range 9-19 weeks), when mean haemoglobin had increased from 7.8 to a stable value of 13.0 g/dl in response to rHuEpo treatment (P < 0.001). Physical working capacity and oxygen uptake at the anaerobic threshold (4 mmol/l blood lactate concentration) increased from 68 +/- 12 to 80 +/- 16 watts and 0.95 +/- 0.14 to 1.10 +/- 0.20 l/min, respectively (P < 0.01). DPG, which determines oxygen affinity to haemoglobin in red cells, increased by 13% from 13.7 +/- 1.5 to 15.5 +/- 2.2 mumol/g Hb (P < 0.05). With maximal exercise mean DPG values significantly decreased to a much lower level without rHuEpo treatment than after correction of anaemia. Therefore rHuEpo treatment results both in better oxygen transport capacity and reduced intraerythrocytic oxygen affinity, which is followed by improved oxygen delivery to tissues per unit of haemoglobin. These effects may explain the improvement of exercise capacity observed in dialysis patients after rHuEpo treatment.

Decreases in maximal oxygen uptake following long-duration spaceflight: Role of convective and diffusive O2 transport mechanisms.

PubMed

Ade, C J; Broxterman, R M; Moore, A D; Barstow, T J

2017-04-01

We have previously predicted that the decrease in maximal oxygen uptake (V̇o 2max ) that accompanies time in microgravity reflects decrements in both convective and diffusive O 2 transport to the mitochondria of the contracting myocytes. The aim of this investigation was therefore to quantify the relative changes in convective O 2 transport (Q̇o 2 ) and O 2 diffusing capacity (Do 2 ) following long-duration spaceflight. In nine astronauts, resting hemoglobin concentration ([Hb]), V̇o 2max , maximal cardiac output (Q̇ Tmax ), and differences in arterial and venous O 2 contents ([Formula: see text]-[Formula: see text]) were obtained retrospectively for International Space Station Increments 19-33 (April 2009-November 2012). Q̇o 2 and Do 2 were calculated from these variables via integration of Fick's Principle of Mass Conservation and Fick's Law of Diffusion. V̇o 2max significantly decreased from pre- to postflight (-53.9 ± 45.5%, P = 0.008). The significant decrease in Q̇ Tmax (-7.8 ± 9.1%, P = 0.05), despite an unchanged [Hb], resulted in a significantly decreased Q̇o 2 (-11.4 ± 10.5%, P = 0.02). Do 2 significantly decreased from pre- to postflight by -27.5 ± 24.5% ( P = 0.04), as did the peak [Formula: see text]-[Formula: see text] (-9.2 ± 7.5%, P = 0.007). With the use of linear regression analysis, changes in V̇o 2max were significantly correlated with changes in Do 2 ( R 2  = 0.47; P = 0.04). These data suggest that spaceflight decreases both convective and diffusive O 2 transport. These results have practical implications for future long-duration space missions and highlight the need to resolve the specific mechanisms underlying these spaceflight-induced changes along the O 2 transport pathway. NEW & NOTEWORTHY Long-duration spaceflight elicited a significant decrease in maximal oxygen uptake. Given the adverse physiological adaptations to microgravity along the O 2 transport pathway that have been reported, an integrative approach to the determinants of postflight maximal oxygen uptake is needed. We demonstrate that both convective and diffusive oxygen transport are decreased following ~6 mo International Space Station missions. Copyright © 2017 the American Physiological Society.

Effect of physical training in cool and hot environments on +Gz acceleration tolerance in women

NASA Technical Reports Server (NTRS)

Brock, P. J.; Sciaraffa, D.; Greenleaf, J. E.

1982-01-01

Acceleration tolerance, plasma volume, and maximal oxygen uptake were measured in 15 healthy women before and after submaximal isotonic exercise training periods in cool and hot environments. The women were divided on the basis of age, maximal oxygen uptake, and +Gz tolerance into three groups: a group that exercised in heat (40.6 C), a group that exercised at a lower temperature (18.7 C), and a sedentary control group that functioned in the cool environment. There was no significant change in the +Gz tolerance in any group after training, and terminal heart rates were similar within each group. It is concluded that induction of moderate acclimation responses without increases in sweat rate or resting plasma volume has no influence on +Gz acceleration tolerance in women.

Induced venous pooling and cardiorespiratory responses to exercise after bed rest

NASA Technical Reports Server (NTRS)

Convertino, V. A.; Sandler, H.; Webb, P.; Annis, J. F.

1982-01-01

Venous pooling induced by a specially constructed garment is investigated as a possible means for reversing the reduction in maximal oxygen uptake regularly observed following bed rest. Experiments involved a 15-day period of bed rest during which four healthy male subjects, while remaining recumbent in bed, received daily 210-min venous pooling treatments from a reverse gradient garment supplying counterpressure to the torso. Results of exercise testing indicate that while maximal oxygen uptake endurance time and plasma volume were reduced and maximal heart rate increased after bed rest in the control group, those parameters remained essentially unchanged for the group undergoing venous pooling treatment. Results demonstrate the importance of fluid shifts and venous pooling within the cardiovascular system in addition to physical activity to the maintenance of cardiovascular conditioning.

Switching the mode of metabolism in the yeast Saccharomyces cerevisiae

PubMed Central

Otterstedt, Karin; Larsson, Christer; Bill, Roslyn M; Ståhlberg, Anders; Boles, Eckhard; Hohmann, Stefan; Gustafsson, Lena

2004-01-01

The biochemistry of most metabolic pathways is conserved from bacteria to humans, although the control mechanisms are adapted to the needs of each cell type. Oxygen depletion commonly controls the switch from respiration to fermentation. However, Saccharomyces cerevisiae also controls that switch in response to the external glucose level. We have generated an S. cerevisiae strain in which glucose uptake is dependent on a chimeric hexose transporter mediating reduced sugar uptake. This strain shows a fully respiratory metabolism also at high glucose levels as seen for aerobic organisms, and switches to fermentation only when oxygen is lacking. These observations illustrate that manipulating a single step can alter the mode of metabolism. The novel yeast strain is an excellent tool to study the mechanisms underlying glucose-induced signal transduction. PMID:15071495

Cardiovascular consequences of bed rest: effect on maximal oxygen uptake

NASA Technical Reports Server (NTRS)

Convertino, V. A.

1997-01-01

Maximal oxygen uptake (VO2max) is reduced in healthy individuals confined to bed rest, suggesting it is independent of any disease state. The magnitude of reduction in VO2max is dependent on duration of bed rest and the initial level of aerobic fitness (VO2max), but it appears to be independent of age or gender. Bed rest induces an elevated maximal heart rate which, in turn, is associated with decreased cardiac vagal tone, increased sympathetic catecholamine secretion, and greater cardiac beta-receptor sensitivity. Despite the elevation in heart rate, VO2max is reduced primarily from decreased maximal stroke volume and cardiac output. An elevated ejection fraction during exercise following bed rest suggests that the lower stroke volume is not caused by ventricular dysfunction but is primarily the result of decreased venous return associated with lower circulating blood volume, reduced central venous pressure, and higher venous compliance in the lower extremities. VO2max, stroke volume, and cardiac output are further compromised by exercise in the upright posture. The contribution of hypovolemia to reduced cardiac output during exercise following bed rest is supported by the close relationship between the relative magnitude (% delta) and time course of change in blood volume and VO2max during bed rest, and also by the fact that retention of plasma volume is associated with maintenance of VO2max after bed rest. Arteriovenous oxygen difference during maximal exercise is not altered by bed rest, suggesting that peripheral mechanisms may not contribute significantly to the decreased VO2max. However reduction in baseline and maximal muscle blood flow, red blood cell volume, and capillarization in working muscles represent peripheral mechanisms that may contribute to limited oxygen delivery and, subsequently, lowered VO2max. Thus, alterations in cardiac and vascular functions induced by prolonged confinement to bed rest contribute to diminution of maximal oxygen uptake and reserve capacity to perform physical work.

Trans sodium crocetinate: functional neuroimaging studies in a hypoxic brain tumor.

PubMed

Sheehan, Jason P; Popp, Britney; Monteith, Stephen; Toulmin, Sushila; Tomlinson, Jennifer; Martin, Jessica; Cifarelli, Christopher P; Lee, Dae-Hee; Park, Deric M

2011-10-01

Intratumoral hypoxia is believed to be exhibited in high-grade gliomas. Trans sodium crocetinate (TSC) has been shown to increase oxygen diffusion to hypoxic tissues. In this research, the authors use oxygen-sensitive PET studies to evaluate the extent of hypoxia in vivo in a glioblastoma model and the effect of TSC on the baseline oxygenation of the tumor. The C6 glioma cells were stereotactically implanted in the right frontal region of rat brains. Formation of intracranial tumors was confirmed on MR imaging. Animals were injected with Copper(II) diacetyl-di(N4-methylthiosemicarbazone) (Cu-ATSM) and then either TSC or saline (6 rats each). Positron emission tomography imaging was performed, and relative uptake values were computed to determine oxygenation within the tumor and normal brain parenchyma. Additionally, TSC or saline was infused into the animals, and carbonic anhydrase 9 (CA9) and hypoxia-inducing factor-1α (HIF-1α) protein expression were measured 1 day afterward. On PET imaging, all glioblastoma tumors demonstrated a statistically significant decrease in uptake of Cu-ATSM compared with the contralateral cerebral hemisphere (p = 0.000002). The mean relative uptake value of the tumor was 3900 (range 2203-6836), and that of the contralateral brain tissue was 1017 (range 488-2304). The mean relative hypoxic tumor volume for the saline group and TSC group (6 rats each) was 1.01 ± 0.063 and 0.69 ± 0.062, respectively (mean ± SEM, p = 0.002). Infusion of TSC resulted in a 31% decrease in hypoxic volume. Immunoblot analysis revealed expression of HIF-1α and CA9 in all tumor specimens. Some glioblastomas exhibit hypoxia that is demonstrable on oxygen-specific PET imaging. It appears that TSC lessens intratumoral hypoxia on functional imaging. Further studies should explore relative hypoxia in glioblastoma and the potential therapeutic gains that can be achieved by lessening hypoxia during delivery of adjuvant treatment.

Ultrastructural and some functional changes in tumor cells treated with stabilized iron oxide nanoparticles.

PubMed

Yurchenko, O V; Todor, I N; Khayetsky, I K; Tregubova, N A; Lukianova, N Yu; Chekhun, V F

2010-12-01

To study the ultrastructure and some functional indexes of tumor cells treated with stabilized iron nanoparticles in vitro. 3-[4,5dimethylthiazol-2-1]-2,5-diphenyltetrazolium bromide (MTT)-test, electron microscopy, polarography with applying of closed Clark's electrode. It was shown that cultivation of cells with stabilized Fe(3)O(4) leads to intracellular accumulation of ferromagnetic nanoparticles. The most active ferromagnetic uptake by cells has been observed after 24 and 48 h of incubation. The presence of ferromagnetic in cells led to altered mitochondrial structure that caused the decrease of oxygen uptake rate in the cells of all studied lines. Ferromagnetic released from the majority of cells via exocytosis or clasmacytosis after a certain period of time. The number of dead cells or cells with severe damage was moderate, so cytotoxic action of stabilized iron oxide nanoparticles was minimal toward the studied cell lines. the presence of ferromagnetic nanoparticles in culture medium led to alterations in mitochondria ultrastructural organization and decrease of oxygen uptake by mitochondria in sensitive and anticancer-drugs resistant cells.

Role of reactive oxygen species in contraction-mediated glucose transport in mouse skeletal muscle

PubMed Central

Sandström, Marie E; Zhang, Shi-Jin; Bruton, Joseph; Silva, José P; Reid, Michael B; Westerblad, Håkan; Katz, Abram

2006-01-01

Exercise increases glucose transport into skeletal muscle via a pathway that is poorly understood. We investigated the role of endogenously produced reactive oxygen species (ROS) in contraction-mediated glucose transport. Repeated contractions increased 2-deoxyglucose (2-DG) uptake roughly threefold in isolated, mouse extensor digitorum longus (fast-twitch) muscle. N-Acetylcysteine (NAC), a non-specific antioxidant, inhibited contraction-mediated 2-DG uptake by ∼50% (P < 0.05 versus control values), but did not significantly affect basal 2-DG uptake or the uptake induced by insulin, hypoxia or 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR, which mimics AMP-mediated activation of AMP-activated protein kinase, AMPK). Ebselen, a glutathione peroxidase mimetic, also inhibited contraction-mediated 2-DG uptake (by almost 60%, P < 0.001 versus control values). Muscles from mice overexpressing Mn2+-dependent superoxide dismutase, which catalyses H2O2 production from superoxide anions, exhibited a ∼25% higher rate of contraction-mediated 2-DG uptake versus muscles from wild-type control mice (P < 0.05). Exogenous H2O2 induced oxidative stress, as judged by an increase in the [GSSG]/[GSH + GSSG] (reduced glutathione + oxidized glutathione) ratio to 2.5 times control values, and this increase was substantially blocked by NAC. Similarly, NAC significantly attenuated contraction-mediated oxidative stress as judged by measurements of glutathione status and the intracellular ROS level with the fluorescent indicator 5-(and-6)-chloromethyl-2′,7′-dichlorodihydrofluorescein (P < 0.05). Finally, contraction increased AMPK activity and phosphorylation ∼10-fold, and NAC blocked ∼50% of these changes. These data indicate that endogenously produced ROS, possibly H2O2 or its derivatives, play an important role in contraction-mediated activation of glucose transport in fast-twitch muscle. PMID:16777943

Effects of continuous vs interval exercise training on oxygen uptake efficiency slope in patients with coronary artery disease.

PubMed

Prado, D M L; Rocco, E A; Silva, A G; Rocco, D F; Pacheco, M T; Silva, P F; Furlan, V

2016-02-01

The oxygen uptake efficiency slope (OUES) is a submaximal index incorporating cardiovascular, peripheral, and pulmonary factors that determine the ventilatory response to exercise. The purpose of this study was to evaluate the effects of continuous exercise training and interval exercise training on the OUES in patients with coronary artery disease. Thirty-five patients (59.3±1.8 years old; 28 men, 7 women) with coronary artery disease were randomly divided into two groups: continuous exercise training (n=18) and interval exercise training (n=17). All patients performed graded exercise tests with respiratory gas analysis before and 3 months after the exercise-training program to determine ventilatory anaerobic threshold (VAT), respiratory compensation point, and peak oxygen consumption (peak VO2). The OUES was assessed based on data from the second minute of exercise until exhaustion by calculating the slope of the linear relation between oxygen uptake and the logarithm of total ventilation. After the interventions, both groups showed increased aerobic fitness (P<0.05). In addition, both the continuous exercise and interval exercise training groups demonstrated an increase in OUES (P<0.05). Significant associations were observed in both groups: 1) continuous exercise training (OUES and peak VO2 r=0.57; OUES and VO2 VAT r=0.57); 2) interval exercise training (OUES and peak VO2 r=0.80; OUES and VO2 VAT r=0.67). Continuous and interval exercise training resulted in a similar increase in OUES among patients with coronary artery disease. These findings suggest that improvements in OUES among CAD patients after aerobic exercise training may be dependent on peripheral and central mechanisms.

Oxygen uptake and blood metabolic responses to a 400-m run.

PubMed

Hanon, Christine; Lepretre, Pierre-Marie; Bishop, David; Thomas, Claire

2010-05-01

This study aimed to investigate the oxygen uptake and metabolic responses during a 400-m run reproducing the pacing strategy used in competition. A portable gas analyser was used to measure the oxygen uptake (VO2) of ten specifically trained runners racing on an outdoor track. The tests included (1) an incremental test to determine maximal VO2 (VO2max) and the velocity associated with VO2(max) (v - VO2max), (2) a maximal 400-m (400T) and 3) a 300-m running test (300T) reproducing the exact pacing pattern of the 400T. Blood lactate, bicarbonate concentrations [HCO3(-)], pH and arterial oxygen saturation were analysed at rest and 1, 4, 7, 10 min after the end of the 400 and 300T. The peak VO2 recorded during the 400T corresponded to 93.9 +/- 3.9% of VO2max and was reached at 24.4 +/- 3.2 s (192 +/- 22 m). A significant decrease in VO2 (P < 0.05) was observed in all subjects during the last 100 m, although the velocity did not decrease below v - VO2max. The VO2 in the last 5 s was correlated with the pH (r = 0.86, P < 0.0005) and [HCO3(-)] (r = 0.70, P < 0.05) measured at the end of 300T. Additionally, the velocity decrease observed in the last 100 m was inversely correlated with [HCO3(-)] and pH at 300T (r = -0.83, P < 0.001, r = -0.69, P < 0.05, respectively). These track running data demonstrate that acidosis at 300 m was related to both the VO2 response and the velocity decrease during the final 100 m of a 400-m run.

Secondary aerosol formation promotes water uptake by organic-rich wildfire haze particles in equatorial Asia

NASA Astrophysics Data System (ADS)

Chen, Jing; Hapsari Budisulistiorini, Sri; Miyakawa, Takuma; Komazaki, Yuichi; Kuwata, Mikinori

2018-06-01

The diameter growth factor (GF) of 100 nm haze particles at 85 % relative humidity (RH) and their chemical characteristics were simultaneously monitored at Singapore in October 2015 during a pervasive wildfire haze episode that was caused by peatland burning in Indonesia. Non-refractory submicron particles (NR-PM1) were dominated by organics (OA; approximating 77.1 % in total mass), whereas sulfate was the most abundant inorganic constituent (11.7 % on average). A statistical analysis of the organic mass spectra showed that most organics (36.0 % of NR-PM1 mass) were highly oxygenated. Diurnal variations of GF, number fractions of more hygroscopic mode particles, mass fractions of sulfate, and mass fractions of oxygenated organics (OOA) synchronized well, peaking during the day. The mean hygroscopicity parameter (κ) of the haze particles was 0.189 ± 0.087, and the mean κ values of organics were 0.157 ± 0.108 (κorg, bulk organics) and 0.266 ± 0.184 (κOOA, OOA), demonstrating the important roles of both sulfate and highly oxygenated organics in the hygroscopic growth of organics-dominated wildfire haze particles. κorg correlated with the water-soluble organic fraction insignificantly, but it positively correlated with f44 (fraction of the ion fragment at m/z 44 in total organics) (R = 0.70), implying the oxygenation degree of organics could be more critical for the water uptake of organic compounds. These results further suggest the importance of sulfate and secondary organic aerosol formation in promoting the hygroscopic growth of wildfire haze particles. Further detailed size-resolved as well as molecular-level chemical information about organics is necessary for the profound exploration of water uptake by wildfire haze particles in equatorial Asia.

Effect of elicitation on growth, respiration, and nutrient uptake of root and cell suspension cultures of Hyoscyamus muticus.

PubMed

Carvalho, Edgard B; Curtis, Wayne R

2002-01-01

The elicitation of Hyoscyamus muticus root and cell suspension cultures by fungal elicitor from Rhizoctonia solani causes dramatic changes in respiration, nutrient yields, and growth. Cells and mature root tissues have similar specific oxygen uptake rates (SOUR) before and after the onset of the elicitation process. Cell suspension SOUR were 11 and 18 micromol O2/g FW x h for non-elicited control and elicited cultures, respectively. Mature root SOUR were 11 and 24 micromol O2/g FW x h for control and elicited tissue, respectively. Tissue growth is significantly reduced upon the addition of elicitor to these cultures. Inorganic yield remains fairly constant, whereas yield on sugar is reduced from 0.532 to 0.352 g dry biomass per g sugar for roots and 0.614 to 0.440 g dry biomass per g sugar for cells. This reduction in yield results from increased energy requirements for the defense response. Growth reduction is reflected in a reduction in root meristem (tip) SOUR, which decreased from 189 to 70 micromol O2/g FW x h upon elicitation. Therefore, despite the increase in total respiration, the maximum local oxygen fluxes are reduced as a result of the reduction in metabolic activity at the meristem. This distribution of oxygen uptake throughout the mature tissue could reduce mass transfer requirements during elicited production. However, this was not found to be the case for sesquiterpene elicitation, where production of lubimin and solavetivone were found to increase linearly up to oxygen partial pressures of 40% O2 in air. SOUR is shown to similarly increase in both bubble column and tubular reactors despite severe mass transfer limitations, suggesting the possibility of metabolically induced increases in tissue convective transport during elicitation.

Effects of Oxygen Supply During Training on Subjects With COPD Who Are Normoxemic at Rest and During Exercise: A Blinded Randomized Controlled Trial.

PubMed

Spielmanns, Marc; Fuchs-Bergsma, Chantal; Winkler, Aurelia; Fox, Gabriele; Krüger, Stefan; Baum, Klaus

2015-04-01

It is well established that physical training enhances functionality and quality of life in patients with COPD. However, little data exist concerning the effects of the usefulness of oxygen supply during exercise training for > 3 months in patients with COPD who are normoxemic at rest and during exercise. We hypothesized that oxygen supply during training sessions enables higher training intensity and thus optimizes training results in patients with COPD. In this blinded randomized controlled study, we carried out a 24-week training program with progressively increasing loads involving large muscle groups. In addition, we compared the influences of oxygen supplementation. Thirty-six subjects with moderate-to-severe COPD who were not dependent on long-term oxygen therapy trained under supervision for 24 weeks (3 times/week at 30 min/session). Subjects were randomized into 2 groups: oxygen supply via nasal cannula at a flow of 4 L/min and compressed air at the same flow throughout the training program. Lung function tests at rest (inspiratory vital capacity, FEV1, Tiffeneau index), cycle spiroergometry (peak ventilation, peak oxygen uptake, peak respiratory exchange rate, submaximal and peak lactic acid concentrations), 6-min walk tests, and quality-of-life assessments (Medical Outcomes Study 36-Item Short Form questionnaire) were conducted before and after 12 and 24 weeks. Independent of oxygen supplementation, statistically significant improvements occurred in quality of life, maximal tolerated load during cycling, peak oxygen uptake, and 6-min walk test after 12 weeks of training. Notably, there were no further improvements from 12 to 24 weeks despite progressively increased training loads. Endurance training 3 times/week resulted in significant improvements in quality of life and exercise capacity in subjects with moderate-to-severe COPD within the initial 12 weeks, followed by a stable period over the following 12 weeks with no further benefits of supplemental oxygen. Copyright © 2015 by Daedalus Enterprises.

Reversible Oxygenation of 2,4-Diaminobutanoic Acid-Co(II) Complexes

PubMed Central

Li, Hui; Yue, Fan; Wen, Hongmei

2016-01-01

This paper introduces the structural characterization and studies on reversible oxygenation behavior of a new oxygen carrier Co(II)-2,4-diaminobutanoic acid (DABA) complex in aqueous solution. The composition of the oxygenated complex was determined by gas volumetric method, molar ratio method, and mass spectrometry, and the formula of the oxygenated complex was determined to be [Co(DABA)2O2]. In aqueous solution, the complex can continuously uptake and release dioxygen and exhibit excellent reversibility of oxygenation and deoxygenation ability. This complex can maintain 50% of its original oxygenation capacity after 30 cycles in 24 h and retain 5% of the original oxygenation capacity after more than 260 cycles after 72 h. When a ligand analogue was linked to histidine (His), the new complex exhibited as excellent reversible oxygenation property as His-Co(II) complex. Insight into the relationship between structural detail and oxygenation properties will provide valuable suggestion for a new family of oxygen carriers. PMID:27648004

The Effects of a Ketogenic Diet on Exercise Metabolism and Physical Performance in Off-Road Cyclists

PubMed Central

Zajac, Adam; Poprzecki, Stanisław; Maszczyk, Adam; Czuba, Miłosz; Michalczyk, Małgorzata; Zydek, Grzegorz

2014-01-01

The main objective of this research was to determine the effects of a long-term ketogenic diet, rich in polyunsaturated fatty acids, on aerobic performance and exercise metabolism in off-road cyclists. Additionally, the effects of this diet on body mass and body composition were evaluated, as well as those that occurred in the lipid and lipoprotein profiles due to the dietary intervention. The research material included eight male subjects, aged 28.3 ± 3.9 years, with at least five years of training experience that competed in off-road cycling. Each cyclist performed a continuous exercise protocol on a cycloergometer with varied intensity, after a mixed and ketogenic diet in a crossover design. The ketogenic diet stimulated favorable changes in body mass and body composition, as well as in the lipid and lipoprotein profiles. Important findings of the present study include a significant increase in the relative values of maximal oxygen uptake (VO2max) and oxygen uptake at lactate threshold (VO2 LT) after the ketogenic diet, which can be explained by reductions in body mass and fat mass and/or the greater oxygen uptake necessary to obtain the same energy yield as on a mixed diet, due to increased fat oxidation or by enhanced sympathetic activation. The max work load and the work load at lactate threshold were significantly higher after the mixed diet. The values of the respiratory exchange ratio (RER) were significantly lower at rest and during particular stages of the exercise protocol following the ketogenic diet. The heart rate (HR) and oxygen uptake were significantly higher at rest and during the first three stages of exercise after the ketogenic diet, while the reverse was true during the last stage of the exercise protocol conducted with maximal intensity. Creatine kinase (CK) and lactate dehydrogenase (LDH) activity were significantly lower at rest and during particular stages of the 105-min exercise protocol following the low carbohydrate ketogenic diet. The alterations in insulin and cortisol concentrations due to the dietary intervention confirm the concept that the glucostatic mechanism controls the hormonal and metabolic responses to exercise. PMID:24979615

The effects of a ketogenic diet on exercise metabolism and physical performance in off-road cyclists.

PubMed

Zajac, Adam; Poprzecki, Stanisław; Maszczyk, Adam; Czuba, Miłosz; Michalczyk, Małgorzata; Zydek, Grzegorz

2014-06-27

The main objective of this research was to determine the effects of a long-term ketogenic diet, rich in polyunsaturated fatty acids, on aerobic performance and exercise metabolism in off-road cyclists. Additionally, the effects of this diet on body mass and body composition were evaluated, as well as those that occurred in the lipid and lipoprotein profiles due to the dietary intervention. The research material included eight male subjects, aged 28.3 ± 3.9 years, with at least five years of training experience that competed in off-road cycling. Each cyclist performed a continuous exercise protocol on a cycloergometer with varied intensity, after a mixed and ketogenic diet in a crossover design. The ketogenic diet stimulated favorable changes in body mass and body composition, as well as in the lipid and lipoprotein profiles. Important findings of the present study include a significant increase in the relative values of maximal oxygen uptake (VO2max) and oxygen uptake at lactate threshold (VO2 LT) after the ketogenic diet, which can be explained by reductions in body mass and fat mass and/or the greater oxygen uptake necessary to obtain the same energy yield as on a mixed diet, due to increased fat oxidation or by enhanced sympathetic activation. The max work load and the work load at lactate threshold were significantly higher after the mixed diet. The values of the respiratory exchange ratio (RER) were significantly lower at rest and during particular stages of the exercise protocol following the ketogenic diet. The heart rate (HR) and oxygen uptake were significantly higher at rest and during the first three stages of exercise after the ketogenic diet, while the reverse was true during the last stage of the exercise protocol conducted with maximal intensity. Creatine kinase (CK) and lactate dehydrogenase (LDH) activity were significantly lower at rest and during particular stages of the 105-min exercise protocol following the low carbohydrate ketogenic diet. The alterations in insulin and cortisol concentrations due to the dietary intervention confirm the concept that the glucostatic mechanism controls the hormonal and metabolic responses to exercise.

Physiological responses and air consumption during simulated firefighting tasks in a subway system.

PubMed

Williams-Bell, F Michael; Boisseau, Geoff; McGill, John; Kostiuk, Andrew; Hughson, Richard L

2010-10-01

Professional firefighters (33 men, 3 women), ranging in age from 30 to 53 years, participated in a simulation of a subway system search and rescue while breathing from their self-contained breathing apparatus (SCBA). We tested the hypothesis that during this task, established by expert firefighters to be of moderate intensity, the rate of air consumption would exceed the capacity of a nominal 30-min cylinder. Oxygen uptake, carbon dioxide output, and air consumption were measured with a portable breath-by-breath gas exchange analysis system, which was fully integrated with the expired port of the SCBA. The task involved descending a flight of stairs, walking, performing a search and rescue, retreat walking, then ascending a single flight of stairs to a safe exit. This scenario required between 9:56 and 13:24 min:s (mean, 12:10 ± 1:10 min:s) to complete, with an average oxygen uptake of 24.3 ± 4.5 mL kg(-1) min(-1) (47 ± 10 % peak oxygen uptake) and heart rate of 76% ± 7% of maximum. The highest energy requirement was during the final single-flight stair climb (30.4 ± 5.4 mL kg(-1) min(-1)). The average respiratory exchange ratio (carbon dioxide output/oxygen uptake) throughout the scenario was 0.95 ± 0.08, indicating a high carbon dioxide output for a relatively moderate average energy requirement. Air consumption from the nominal "30-min" cylinder averaged 51% (range, 26%-68%); however, extrapolation of these rates of consumption suggested that the low-air alarm, signalling that only 25% of the air remains, would have occurred as early as 11 min for an individual with the highest rate of air consumption, and at 16 min for the group average. These data suggest that even the moderate physical demands of walking combined with search and rescue while wearing full protective gear and breathing through the SCBA impose considerable physiological strain on professional firefighters. As well, the rate of air consumption in these tasks classed as moderate, compared with high-rise firefighting, would have depleted the air supply well before the nominal time used to describe the cylinders.

Respiratory control in aquatic insects dictates their vulnerability to global warming

PubMed Central

Verberk, Wilco C. E. P.; Bilton, David T.

2013-01-01

Forecasting species responses to climatic warming requires knowledge of how temperature impacts may be exacerbated by other environmental stressors, hypoxia being a principal example in aquatic systems. Both stressors could interact directly as temperature affects both oxygen bioavailability and ectotherm oxygen demand. Insufficient oxygen has been shown to limit thermal tolerance in several aquatic ectotherms, although, the generality of this mechanism has been challenged for tracheated arthropods. Comparing species pairs spanning four different insect orders, we demonstrate that oxygen can indeed limit thermal tolerance in tracheates. Species that were poor at regulating oxygen uptake were consistently more vulnerable to the synergistic effects of warming and hypoxia, demonstrating the importance of respiratory control in setting thermal tolerance limits. PMID:23925834

Respiratory control in aquatic insects dictates their vulnerability to global warming.

PubMed

Verberk, Wilco C E P; Bilton, David T

2013-10-23

Forecasting species responses to climatic warming requires knowledge of how temperature impacts may be exacerbated by other environmental stressors, hypoxia being a principal example in aquatic systems. Both stressors could interact directly as temperature affects both oxygen bioavailability and ectotherm oxygen demand. Insufficient oxygen has been shown to limit thermal tolerance in several aquatic ectotherms, although, the generality of this mechanism has been challenged for tracheated arthropods. Comparing species pairs spanning four different insect orders, we demonstrate that oxygen can indeed limit thermal tolerance in tracheates. Species that were poor at regulating oxygen uptake were consistently more vulnerable to the synergistic effects of warming and hypoxia, demonstrating the importance of respiratory control in setting thermal tolerance limits.

Oxygen content tailored magnetic and electronic properties in cobaltite double perovskite thin films

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

Harrell, Zach John; Enriquez, Erik M.; Chen, Aiping

Oxygen content in transition metal oxides is one of the most important parameters to control for the desired physical properties. Recently, we have systematically studied the oxygen content and property relationship of the double perovskite PrBaCo 2O 5.5+δ (PBCO) thin films deposited on the LaAlO 3 substrates. The oxygen content in the films was varied by in-situ annealing in a nitrogen, oxygen, or ozone environment. Associated with the oxygen content, the out-of-plane lattice parameter progressively decreases with increasing oxygen content in the films. The saturated magnetization shows a drastic increase and resistivity is significantly reduced in the ozone annealed samples,more » indicating the strong coupling between physical properties and oxygen content. Furthermore, these results demonstrate that the magnetic properties of PBCO films are highly dependent on the oxygen contents, or the film with higher oxygen uptake has the largest magnetization.« less

Oxygen content tailored magnetic and electronic properties in cobaltite double perovskite thin films

DOE PAGES

Harrell, Zach John; Enriquez, Erik M.; Chen, Aiping; ...

2017-02-27

Oxygen content in transition metal oxides is one of the most important parameters to control for the desired physical properties. Recently, we have systematically studied the oxygen content and property relationship of the double perovskite PrBaCo 2O 5.5+δ (PBCO) thin films deposited on the LaAlO 3 substrates. The oxygen content in the films was varied by in-situ annealing in a nitrogen, oxygen, or ozone environment. Associated with the oxygen content, the out-of-plane lattice parameter progressively decreases with increasing oxygen content in the films. The saturated magnetization shows a drastic increase and resistivity is significantly reduced in the ozone annealed samples,more » indicating the strong coupling between physical properties and oxygen content. Furthermore, these results demonstrate that the magnetic properties of PBCO films are highly dependent on the oxygen contents, or the film with higher oxygen uptake has the largest magnetization.« less

A highly active ATP-insensitive K+ import pathway in plant mitochondria.

PubMed

Ruy, Fernando; Vercesi, Anibal E; Andrade, Paula B M; Bianconi, M Lucia; Chaimovich, Hernan; Kowaltowski, Alicia J

2004-04-01

We describe here a regulated and highly active K+ uptake pathway in potato (Solanum tuberosum), tomato (Lycopersicon esculentum), and maize (Zea mays) mitochondria. K+ transport was not inhibited by ATP, NADH, or thiol reagents, which regulate ATP-sensitive K+ channels previously described in plant and mammalian mitochondria. However, K+ uptake was completely prevented by quinine, a broad spectrum K+ channel inhibitor. Increased K+ uptake in plants leads to mitochondrial swelling, respiratory stimulation, heat release, and the prevention of reactive oxygen species formation. This newly described ATP-insensitive K+ import pathway is potentially involved in metabolism regulation and prevention of oxidative stress.

Cardiorespiratory collapse at high temperature in swimming adult sockeye salmon

PubMed Central

Eliason, Erika J.; Clark, Timothy D.; Hinch, Scott G.; Farrell, Anthony P.

2013-01-01

Elevated summer river temperatures are associated with high in-river mortality in adult sockeye salmon (Oncorhynchus nerka) during their once-in-a-lifetime spawning migration up the Fraser River (British Columbia, Canada). However, the mechanisms underlying the decrease in whole-animal performance and cardiorespiratory collapse above optimal temperatures for aerobic scope (Topt) remain elusive for aquatic ectotherms. This is in part because all the relevant cardiorespiratory variables have rarely been measured directly and simultaneously during exercise at supra-optimal temperatures. Using the oxygen- and capacity-limited thermal tolerance hypothesis as a framework, this study simultaneously and directly measured oxygen consumption rate (MO2), cardiac output , heart rate (fH), and cardiac stroke volume (Vs), as well as arterial and venous blood oxygen status in adult sockeye salmon swimming at temperatures that bracketed Topt to elucidate possible limitations in oxygen uptake into the blood or internal delivery through the oxygen cascade. Above Topt, the decline in MO2max and aerobic scope was best explained by a cardiac limitation, triggered by reduced scope for fH. The highest test temperatures were characterized by a negative scope for fH, dramatic decreases in maximal and maximal Vs, and cardiac dysrhythmias. In contrast, arterial blood oxygen content and partial pressure were almost insensitive to supra-optimal temperature, suggesting that oxygen delivery to and uptake by the gill were not a limiting factor. We propose that the high-temperature-induced en route mortality in migrating sockeye salmon may be at least partly attributed to physiological limitations in aerobic performance due to cardiac collapse via insufficient scope for fH. Furthermore, this improved mechanistic understanding of cardiorespiratory collapse at high temperature is likely to have broader application to other salmonids and perhaps other aquatic ectotherms. PMID:27293592

Cardiorespiratory collapse at high temperature in swimming adult sockeye salmon.

PubMed

Eliason, Erika J; Clark, Timothy D; Hinch, Scott G; Farrell, Anthony P

2013-01-01

Elevated summer river temperatures are associated with high in-river mortality in adult sockeye salmon (Oncorhynchus nerka) during their once-in-a-lifetime spawning migration up the Fraser River (British Columbia, Canada). However, the mechanisms underlying the decrease in whole-animal performance and cardiorespiratory collapse above optimal temperatures for aerobic scope (T opt) remain elusive for aquatic ectotherms. This is in part because all the relevant cardiorespiratory variables have rarely been measured directly and simultaneously during exercise at supra-optimal temperatures. Using the oxygen- and capacity-limited thermal tolerance hypothesis as a framework, this study simultaneously and directly measured oxygen consumption rate (MO2), cardiac output [Formula: see text], heart rate (f H), and cardiac stroke volume (V s), as well as arterial and venous blood oxygen status in adult sockeye salmon swimming at temperatures that bracketed T opt to elucidate possible limitations in oxygen uptake into the blood or internal delivery through the oxygen cascade. Above T opt, the decline in MO2max and aerobic scope was best explained by a cardiac limitation, triggered by reduced scope for f H. The highest test temperatures were characterized by a negative scope for f H, dramatic decreases in maximal [Formula: see text] and maximal V s, and cardiac dysrhythmias. In contrast, arterial blood oxygen content and partial pressure were almost insensitive to supra-optimal temperature, suggesting that oxygen delivery to and uptake by the gill were not a limiting factor. We propose that the high-temperature-induced en route mortality in migrating sockeye salmon may be at least partly attributed to physiological limitations in aerobic performance due to cardiac collapse via insufficient scope for f H. Furthermore, this improved mechanistic understanding of cardiorespiratory collapse at high temperature is likely to have broader application to other salmonids and perhaps other aquatic ectotherms.

Gas adsorption capacity of wood pellets

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

Yazdanpanah, F.; Sokhansanj, Shahabaddine; Lim, C. Jim

In this paper, temperature-programmed desorption (TPD) analysis was used to measure and analyze the adsorption of off-gases and oxygen by wood pellets during storage. Such information on how these gases interact with the material helps in the understanding of the purging/stripping behavior of off-gases to develop effective ventilation strategies for wood pellets. Steam-exploded pellets showed the lowest carbon dioxide (CO 2) uptake compared to the regular and torrefied pellets. The high CO 2 adsorption capacity of the torrefied pellets could be attributed to their porous structure and therefore greater available surface area. Quantifying the uptake of carbon monoxide by pelletsmore » was challenging due to chemical adsorption, which formed a strong bond between the material and carbon monoxide. The estimated energy of desorption for CO (97.8 kJ/mol) was very high relative to that for CO 2 (7.24 kJ/mol), demonstrating the mechanism of chemical adsorption and physical adsorption for CO and CO 2, respectively. As for oxygen, the strong bonds that formed between the material and oxygen verified the existence of chemical adsorption and formation of an intermediate material.« less

[Respiration of wheat root cells under simultaneous inhibition of parts I and III of the electron transport chain of mitochondria by rotenone and antimycine A].

PubMed

Rakhmatullina, D F; Gordon, L Kh; Ogorodnikova, T I

2005-01-01

Respiration of excised roots of 5 day old wheat seedlings with blocked mitochondrial oxidation under simultaneous action of rotenone and antimycine A was studied. A reduced rate of oxygen uptake was observed within the first hour of root treatment inhibitors. However, after a 5 h exposure there was an increase in oxygen uptake, which was prevented by KCN but amplified by malate and ascorbate. The application of inhibitors caused a considerable increase in the respiratory coefficient (RC) up to 2.1, that suggests a significant CO2 release, when the initial sites of mitochondrial electron transport chain were inhibited. RC did not raise, when ascorbate was added in the presence of inhibitors. We assume that inhibition of mitochondrial oxidation at I and III sites of electron transport chain facilitates switching on the alternative paths of reductant translocation to oxygen. Participation of ATPases and redox system of plasma membrane in the response reactions of respiration directed to the restoration of ion, particularly, proton homeostasis in conditions of inhibited mitochondrial oxidation is discussed.

Complexing Methylene Blue with Phosphorus Dendrimers to Increase Photodynamic Activity.

PubMed

Dabrzalska, Monika; Janaszewska, Anna; Zablocka, Maria; Mignani, Serge; Majoral, Jean Pierre; Klajnert-Maculewicz, Barbara

2017-02-23

The efficiency of photodynamic therapy is limited mainly due to low selectivity, unfavorable biodistribution of photosensitizers, and long-lasting skin sensitivity to light. However, drug delivery systems based on nanoparticles may overcome the limitations mentioned above. Among others, dendrimers are particularly attractive as carriers, because of their globular architecture and high loading capacity. The goal of the study was to check whether an anionic phosphorus dendrimer is suitable as a carrier of a photosensitizer-methylene blue (MB). As a biological model, basal cell carcinoma cell lines were used. We checked the influence of the MB complexation on its singlet oxygen production ability using a commercial fluorescence probe. Next, cellular uptake, phototoxicity, reactive oxygen species (ROS) generation, and cell death were investigated. The MB-anionic dendrimer complex (MB-1an) was found to generate less singlet oxygen; however, the complex showed higher cellular uptake and phototoxicity against basal cell carcinoma cell lines, which was accompanied with enhanced ROS production. Owing to the obtained results, we conclude that the photodynamic activity of MB complexed with an anionic dendrimer is higher than free MB against basal cell carcinoma cell lines.

Gas adsorption capacity of wood pellets

DOE PAGES

Yazdanpanah, F.; Sokhansanj, Shahabaddine; Lim, C. Jim; ...

2016-02-03

In this paper, temperature-programmed desorption (TPD) analysis was used to measure and analyze the adsorption of off-gases and oxygen by wood pellets during storage. Such information on how these gases interact with the material helps in the understanding of the purging/stripping behavior of off-gases to develop effective ventilation strategies for wood pellets. Steam-exploded pellets showed the lowest carbon dioxide (CO 2) uptake compared to the regular and torrefied pellets. The high CO 2 adsorption capacity of the torrefied pellets could be attributed to their porous structure and therefore greater available surface area. Quantifying the uptake of carbon monoxide by pelletsmore » was challenging due to chemical adsorption, which formed a strong bond between the material and carbon monoxide. The estimated energy of desorption for CO (97.8 kJ/mol) was very high relative to that for CO 2 (7.24 kJ/mol), demonstrating the mechanism of chemical adsorption and physical adsorption for CO and CO 2, respectively. As for oxygen, the strong bonds that formed between the material and oxygen verified the existence of chemical adsorption and formation of an intermediate material.« less

In vitro and in vivo evaluations of a hydrophilic 64Cu-bis(thiosemicarbazonato)-glucose conjugate for hypoxia imaging.

PubMed

Bayly, Simon R; King, Robert C; Honess, Davina J; Barnard, Peter J; Betts, Helen M; Holland, Jason P; Hueting, Rebekka; Bonnitcha, Paul D; Dilworth, Jonathan R; Aigbirhio, Franklin I; Christlieb, Martin

2008-11-01

A water-soluble glucose conjugate of the hypoxia tracer 64Cu-diacetyl-bis(N4-methylthiosemicarbazone) (64Cu-ATSM) was synthesized and radiolabeled (64Cu-ATSE/A-G). Here we report our initial biological experiments with 64Cu-ATSE/A-G and compare the results with those obtained for 64Cu-ATSM and 18F-FDG. The uptake of 64Cu-ATSE/A-G and 64Cu-ATSM into HeLa cells in vitro was investigated at a range of dissolved oxygen concentrations representing normoxia, hypoxia, and anoxia. Small-animal PET with 64Cu-ATSE/A-G was performed in male BDIX rats implanted with P22 syngeneic carcinosarcomas. Images of 64Cu-ATSM and 18F-FDG were obtained in the same model for comparison. 64CuATSE/A-G showed oxygen concentration-dependent uptake in vitro and, under anoxic conditions, showed slightly lower levels of cellular uptake than 64Cu-ATSM; uptake levels under hypoxic conditions were also lower. Whereas the normoxic uptake of 64Cu-ATSM increased linearly over time, 64Cu-ATSE/A-G uptake remained at low levels over the entire time course. In the PET study, 64CuATSE/A-G showed good tumor uptake and a biodistribution pattern substantially different from that of each of the controls. In marked contrast to the findings for 64Cu-ATSM, renal clearance and accumulation in the bladder were observed. 64Cu-ATSE/A-G did not display the characteristic brain and heart uptake of 18F-FDG. The in vitro cell uptake studies demonstrated that 64Cu-ATSE/A-G retained hypoxia selectivity and had improved characteristics when compared with 64Cu-ATSM. The in vivo PET results indicated a difference in the excretion pathways, with a shift from primarily hepatointestinal for 64Cu-ATSM to partially renal with 64Cu-ATSE/A-G. This finding is consistent with the hydrophilic nature of the glucose conjugate. A comparison with 18F-FDG PET results revealed that 64Cu-ATSE/A-G was not a surrogate for glucose metabolism. We have demonstrated that our method for the modification of Cu-bis(thiosemicarbazonato) complexes allows their biodistribution to be modified without negating their hypoxia selectivity or tumor uptake properties.

[Crabtree effect caused by ketoses in isolated rat hepatocytes].

PubMed

Martínez, P; Carrascosa, J M; Núñez de Castro, I

1982-01-01

Oxygen uptake and glycolytic activity were studied in hepatocytes isolated from fed rats. The addition of fructose or tagatose resulted in a 38% and 31% inhibition of cellular respiration respectively. The addition of 10 mM D-glyceraldehyde caused a slight Crabtree effect. Glucose, L-sorbose, or glycerol failed to modify oxygen consumption. Only incubation in the presence of fructose showed a high aerobic glycolysis measured by lactate production.

Mechanisms underlying the protective effects of myricetin and quercetin following oxygen/glucose deprivation-induced cell swelling and the reduction in glutamate uptake in glial cells

USDA-ARS?s Scientific Manuscript database

C6 glial cells were exposed to oxygen-glucose deprivation (OGD) in cell culture for 5 hr and cell swelling was determined 90 min after the end of OGD. The OGD-induced increase in swelling was significantly blocked by the two flavonoids studied, quercetin and myricetin. The OGD-induced increase in ...

Direct oxygen uptake from air by novel glycogen accumulating organism dominated biofilm minimizes excess sludge production.

PubMed

Hossain, Md Iqbal; Paparini, Andrea; Cord-Ruwisch, Ralf

2018-05-29

The cost associated with treatment and disposal of excess sludge produced is one of the greatest operational expenses in wastewater treatment plants. In this study, we quantify and explain greatly reduced excess sludge production in the novel glycogen accumulating organism (GAO) dominated drained biofilm system previously shown to be capable of extremely energy efficient removal of organic carbon (biological oxygen demand or BOD) from wastewater. The average excess sludge production rate was 0.05 g VSS g -1 BOD (acetate) removed, which is about 9-times lower than that of comparative studies using the same acetate based synthetic wastewater. The substantially lower sludge yield was attributed to a number of features such as the high oxygen consumption facilitated by direct oxygen uptake from air, high biomass content (21.41 g VSS L -1 of reactor), the predominance of the GAO (Candidatus competibacter) with a low growth yield and the overwhelming presence of the predatory protozoa (Tetramitus) in the biofilm. Overall, the combination of low-energy requirement for air supply (no compressed air supply) and the low excess sludge production rate, could make this novel "GAO drained biofilm" process one of the most economical ways of biological organic carbon removal from wastewater. Copyright © 2018. Published by Elsevier B.V.

The Effect of Size of Red Cells on the Kinetics of Their Oxygen Uptake

PubMed Central

Holland, R. A. B.; Forster, R. E.

1966-01-01

Using a double-beam stopped-flow apparatus estimations were made of the velocity constant for the initial uptake of oxygen by fully reduced erythrocytes (k'c). Mammalian cells were studied with volumes varying from 20 µ3 (goat) to 90 µ3 (man), as were bullfrog cells (680 µ3). Measurements were made under physiological conditions of pH, P CO2, and temperature. In man k'c was 80 mM -1 sec-1 and in other species smaller cells generally had a greater value for k'c than did the larger cells. In the goat it was 1.8 times as great as the human value; in the bullfrog it was only one-fifth as great. These differences could not be accounted for by interspecific differences in hemoglobin kinetics. The differences probably represent a true effect of size conferring some biological advantage on the species with the smaller cells. The cell membrane offered resistance to oxygen passage. Using the usual red cell model of an infinite sheet of reduced hemoglobin, membrane permeability appeared to differ among mammals. If, as is likely, the effective cell halfthickness differs among mammals, actual membrane permeability differences may be less. A method for measurement of oxygen saturation of dilute cell suspensions is also described. PMID:5943611

A comparison of head motion and prefrontal haemodynamics during upright and recumbent cycling exercise.

PubMed

Tempest, Gavin D; Eston, Roger G; Parfitt, Gaynor

2017-11-01

The aim of this observational study was to compare head motion and prefrontal haemodynamics during exercise using three commercial cycling ergometers. Participants (n = 12) completed an incremental exercise test to exhaustion during upright, recumbent and semi-recumbent cycling. Head motion (using accelerometry), physiological data (oxygen uptake, end-tidal carbon dioxide [P ET CO 2 ] and heart rate) and changes in prefrontal haemodynamics (oxygenation, deoxygenation and blood volume using near infrared spectroscopy [NIRS]) were recorded. Despite no difference in oxygen uptake and heart rate, head motion was higher and P ET CO 2 was lower during upright cycling at maximal exercise (P<0·05). Analyses of covariance (covariates: head motion P>0·05; P ET CO 2 , P<0·01) revealed that prefrontal oxygenation was higher during semi-recumbent than recumbent cycling and deoxygenation and blood volume were higher during upright than recumbent and semi-recumbent cycling (respectively; P<0·05). This work highlights the robustness of the utility of NIRS to head motion and describes the potential postural effects upon the prefrontal haemodynamic response during upright and recumbent cycling exercise. © 2016 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Cell type-dependent uptake, localization, and cytotoxicity of 1.9 nm gold nanoparticles

PubMed Central

Coulter, Jonathan A; Jain, Suneil; Butterworth, Karl T; Taggart, Laura E; Dickson, Glenn R; McMahon, Stephen J; Hyland, Wendy B; Muir, Mark F; Trainor, Coleman; Hounsell, Alan R; O’Sullivan, Joe M; Schettino, Giuseppe; Currell, Fred J; Hirst, David G; Prise, Kevin M

2012-01-01

Background This follow-up study aims to determine the physical parameters which govern the differential radiosensitization capacity of two tumor cell lines and one immortalized normal cell line to 1.9 nm gold nanoparticles. In addition to comparing the uptake potential, localization, and cytotoxicity of 1.9 nm gold nanoparticles, the current study also draws on comparisons between nanoparticle size and total nanoparticle uptake based on previously published data. Methods We quantified gold nanoparticle uptake using atomic emission spectroscopy and imaged intracellular localization by transmission electron microscopy. Cell growth delay and clonogenic assays were used to determine cytotoxicity and radiosensitization potential, respectively. Mechanistic data were obtained by Western blot, flow cytometry, and assays for reactive oxygen species. Results Gold nanoparticle uptake was preferentially observed in tumor cells, resulting in an increased expression of cleaved caspase proteins and an accumulation of cells in sub G1 phase. Despite this, gold nanoparticle cytotoxicity remained low, with immortalized normal cells exhibiting an LD50 concentration approximately 14 times higher than tumor cells. The surviving fraction for gold nanoparticle-treated cells at 3 Gy compared with that of untreated control cells indicated a strong dependence on cell type in respect to radiosensitization potential. Conclusion Gold nanoparticles were most avidly endocytosed and localized within cytoplasmic vesicles during the first 6 hours of exposure. The lack of significant cytotoxicity in the absence of radiation, and the generation of gold nanoparticle-induced reactive oxygen species provide a potential mechanism for previously reported radiosensitization at megavoltage energies. PMID:22701316

Running economy : the forgotten factor in elite performance.

PubMed

Foster, Carl; Lucia, Alejandro

2007-01-01

Running performance depends on maximal oxygen uptake (VO(2max)), the ability to sustain a high percentage of VO(2max) for an extended period of time and running economy. Running economy has been studied relatively less than the other factors. Running economy, measured as steady state oxygen uptake (VO(2)) at intensities below the ventilatory threshold is the standard method. Extrapolation to a common running speed (268 m/min) or as the VO(2) required to run a kilometer is the standard method of assessment. Individuals of East African origin may be systematically more economical, although a smaller body size and a thinner lower leg may be the primary factors. Strategies for improving running economy remain to be developed, although it appears that high intensity running may be a common element acting to improve economy.

Exercise Training During +Gz Acceleration

NASA Technical Reports Server (NTRS)

Greenleaf, J. E.; Chou, J. L.; Simonson, S. R.; Jackson, C. G. R.; Barnes, P. R.

1999-01-01

The overall purpose is to study the effect of passive (without exercise) and active (with exercise) +Gz (head-to-foot) acceleration training, using a short-arm (1.9m radius) centrifuge, on post- training maximal oxygen uptake (VO2 max, work capacity) and 70 deg head-up tilt (orthostatic) tolerance in ambulatory subjects to test the hypothesis that (a) both passive and active acceleration training will improve post-training tilt-tolerance, and (b) there will be no difference in tilt-tolerance between passive and active exercise acceleration training because increased hydrostatic and blood pressures, rather than increased muscular metabolism, will provide the major adaptive stimulus. The purpose of the pilot study was to test the hypothesis that there would be no significant difference in the metabolic responses (oxygen uptake, heart rate, pulmonary ventilation, or respiratory exchange ratio) during supine exercise with moderate +Gz acceleration.

[Dynamics of oxygen uptake during a 100 m front crawl event, performed during competition ].

PubMed

Jalab, Chadi; Enea, Carina; Delpech, Nathalie; Bernard, Olivier

2011-04-01

The main purpose of this study is to estimate the dynamics of oxygen uptake (VO2) during a 100 m front crawl event, performed in competition conditions. Eleven trained swimmers participated in 2 separate sessions, in a 25 m swimming pool. Maximal oxygen uptake (VO2max) was determined during a 400 m maximal event. Swimmers also performed a 100 m front crawl in competition conditions, and then, 3 tests (25, 50, and 75 m) following the pacing strategy of the 100 m event. To be free of technical constraints, VO2 was not measured during the tests, but before and just at the end of each test with a 1 min breath-by-breath method. Each post-test VO2 measurement (after 25, 50, 75, and 100 m) allows us to reconstruct the VO2 kinetics of the 100 m performance. Our results differ from previous studies in that VO2 increases faster in the first half of the race (at 50 m, VO2 ≈ 94% VO2max), reaches VO2max at the 75 m mark; then a decrease in VO2 corresponding to 7% of VO2max appears during the last 25 m. These differences are supposed to be mainly the consequences of the adoption of technical elements and a pacing strategy similar to competition conditions. In the future, these observations may lead to different considerations of the bioenergetic contributions.

Dynamics of oxygen and carbon dioxide in rhizospheres of Lobelia dortmanna - a planar optode study of belowground gas exchange between plants and sediment.

PubMed

Lenzewski, Nikola; Mueller, Peter; Meier, Robert Johannes; Liebsch, Gregor; Jensen, Kai; Koop-Jakobsen, Ketil

2018-04-01

Root-mediated CO 2 uptake, O 2 release and their effects on O 2 and CO 2 dynamics in the rhizosphere of Lobelia dortmanna were investigated. Novel planar optode technology, imaging CO 2 and O 2 distribution around single roots, provided insights into the spatiotemporal patterns of gas exchange between roots, sediment and microbial community. In light, O 2 release and CO 2 uptake were pronounced, resulting in a distinct oxygenated zone (radius: c. 3 mm) and a CO 2 -depleted zone (radius: c. 2 mm) around roots. Simultaneously, however, microbial CO 2 production was stimulated within a larger zone around the roots (radius: c. 10 mm). This gave rise to a distinct pattern with a CO 2 minimum at the root surface and a CO 2 maximum c. 2 mm away from the root. In darkness, CO 2 uptake ceased, and the CO 2 -depleted zone disappeared within 2 h. By contrast, the oxygenated root zone remained even after 8 h, but diminished markedly over time. A tight coupling between photosynthetic processes and the spatiotemporal dynamics of O 2 and CO 2 in the rhizosphere of Lobelia was demonstrated, and we suggest that O 2 -induced stimulation of the microbial community in the sediment increases the supply of inorganic carbon for photosynthesis by building up a CO 2 reservoir in the rhizosphere. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

The efficacy and safety of whole-body electromyostimulation in applying to human body: based from graded exercise test.

PubMed

Jee, Yong-Seok

2018-02-01

Recently, whole body-electromyostimulation (WB-EMS) has upgraded its functions and capabilities and has overcome limitations and inconveniences from past systems. Although the efficacy and safety of EMS have been examined in some studies, specific guidelines for applying WB-EMS are lacking. To determine the efficacy and safety of applying it in healthy men to improve cardiopulmonary and psychophysiological variables when applying WB-EMS. Sixty-four participants were randomly grouped into control group (without electrical stimuli) or WB-EMS group after a 6-week baseline period. The control group (n=33; female. 15; male, 18) wore the WB-EMS suit as much as the WB-EMS group (n=31; female, 15; male, 16). There were no abnormal changes in the cardiopulmonary variables (heart rate, systolic blood pressure [SBP], diastolic blood pressure, and oxygen uptake) during or after the graded exercise test (GXT) in both groups. There was a significant decrease in SBP and an increase of oxygen uptake from stages 3 to 5 of the GXT in the WB-EMS group. The psychophysiological factors for a WB-EMS group, which consisted of soreness, anxiety, fatigability, and sleeplessness were significantly decreased after the experiment. The application of WB-EMS in healthy young men did not negatively affect the cardiopulmonary and psychophysiological factors. Rather, the application of WB-EMS improved SBP and oxygen uptake in submaximal and maximal stages of GXT. This study also confirmed that 6 weeks of WB-EMS training can improve psychophysiological factors.

Responsive measures to prehabilitation in patients undergoing bowel resection surgery.

PubMed

Kim, Do Jun; Mayo, Nancy E; Carli, Franco; Montgomery, David L; Zavorsky, Gerald S

2009-02-01

Surgical patients often show physiological and metabolic distress, muscle weakness, and long hospital stays. Physical conditioning might help recovery. We attempted to identify the most responsive measure of aerobic fitness from a four-week pre-surgical aerobic exercise program (prehabilitation) in patients undergoing major bowel resection. Twenty-one subjects randomized two to one (exercise: control) scheduled for colorectal surgery. Fourteen subjects [Body Mass Index (BMI) = 27 +/- 6 kg/m(2); maximal oxygen uptake (VO(2max)) = 22 +/- 10 ml/kg/min] underwent 3.8 +/- 1.2 weeks (27 +/- 8 sessions) of progressive, structured pre-surgical aerobic exercise training at 40 to 65% of heart rate reserve (%HRR). Peak power output was the only maximal measure that was responsive to training [26 +/- 27%, Effects Size (ES) = 0.24; Standardized Response Mean (SRM) = 1.05; p < 0.05]. For the submaximal measures, heart rate and oxygen uptake during submaximal exercise was most responsive to training (decrease by 13% +/- 15%, ES = -0.24; SRM = -0.57; and 7% +/- 6%, ES = -0.40; SRM -0.97; p < 0.05) at an exercise intensity of 76 +/- 47 W. There was no change to maximal or submaximal measures in the control group. The distance walked over six minutes improved in both groups (by approximately 30 m), but the effect size and t-statistic were higher in the exercise group. Heart rate and oxygen uptake during submaximal exercise, and peak power output are the most responsive measures to four weeks of prehabilitation in subjects with low initial fitness.

Monolayer to MTS: using SEM, HIM, TEM and SERS to compare morphology, nanosensor uptake and redox potential in MCF7 cells

NASA Astrophysics Data System (ADS)

Jamieson, L. E.; Bell, A. P.; Harrison, D. J.; Campbell, C. J.

2015-06-01

Cellular redox potential is important for the control and regulation of a vast number of processes occurring in cells. When the fine redox potential balance within cells is disturbed it can have serious consequences such as the initiation or progression of disease. It is thought that a redox gradient develops in cancer tumours where the peripheral regions are well oxygenated and internal regions, further from vascular blood supply, become starved of oxygen and hypoxic. This makes treatment of these areas more challenging as, for example, radiotherapy relies on the presence of oxygen. Currently techniques for quantitative analysis of redox gradients are limited. Surface enhanced Raman scattering (SERS) nanosensors (NS) have been used to detect redox potential in a quantitative manner in monolayer cultured cells with many advantages over other techniques. This technique has considerable potential for use in multicellular tumour spheroids (MTS) - a three dimensional (3D) cell model which better mimics the tumour environment and gradients that develop. MTS are a more realistic model of the in vivo cellular morphology and environment and are becoming an increasingly popular in vitro model, replacing traditional monolayer culture. Imaging techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM) and helium ion microscopy (HIM) were used to investigate differences in morphology and NS uptake in monolayer culture compared to MTS. After confirming NS uptake, the first SERS measurements revealing quantitative information on redox potential in MTS were performed.

The most economical cadence increases with increasing workload.

PubMed

Foss, Øivind; Hallén, Jostein

2004-08-01

Several studies have suggested that the most economical cadence in cycling increases with increasing workload. However, none of these studies have been able to demonstrate this relationship with experimental data. The purpose of this study was to test the hypothesis that the most economical cadence in elite cyclists increases with increasing workload and to explore the effect of cadence on performance. Six elite road cyclists performed submaximal and maximal tests at four different cadences (60, 80, 100 and 120 rpm) on separate days. Respiratory data was measured at 0, 50, 125, 200, 275 and 350 W during the submaximal test and at the end of the maximal test. The maximal test was carried out as an incremental test, conducted to reveal differences in maximal oxygen uptake and time to exhaustion (short-term performance) between cadences. The results showed that the lowest oxygen uptake, i.e. the best work economy, shifted from 60 rpm at 0 W to 80 rpm at 350 W ( P<0.05). No difference was found in maximal oxygen uptake among cadences ( P>0.05), while the best performance was attained at the same cadence that elicited the best work economy (80 rpm) at 350 W ( P<0.05). This study demonstrated that the most economical cadence increases with increasing workload in elite cyclists. It was further shown that work economy and performance are related during short efforts (approximately 5 min) over a wide range of cadences.

Exercise intensities during a ballet lesson in female adolescents with different technical ability.

PubMed

Guidetti, L; Gallotta, M C; Emerenziani, G P; Baldari, C

2007-09-01

To investigate the exercise intensity during a typical grade five ballet lesson, thirty-nine dancers (13 - 16 yrs) were divided into three different technical proficiency groups: low level (n = 13), intermediate level (n = 14), and high level (n = 12). A progressively incremented treadmill test was administered to determine VO(2max), individual ventilatory threshold (IVT), and the individual anaerobic threshold (IAT). Oxygen uptake (VO(2)), heart rate (HR) and blood lactate (La) were then evaluated during a grade five ballet lesson. Oxygen uptake at IVT, IAT and maximal oxygen uptake were greater (p < 0.05) in the high-level dancers indicating a higher level of fitness. HR and %VO(2max) obtained during the various exercises of the ballet lesson were similar among groups. During the ballet lesson, low technical level dancers had more V.O (2) and La values above (p < 0.05) the IAT than the other groups. Correlation analysis revealed that the number of exercises performed above IAT was positively related to anthropometric characteristics (BMI, %FM; r = 0.36, p < 0.05; r = 0.46, p < 0.01), negatively related to fitness parameters (VO(2IVT), VO(2IAT), VO(2max); r between - 0.43 and - 0.69; p < 0.001) and to technical level (r = - 0.70; p < 0.001). The subjects classified as having low technical abilities had lower fitness levels and performed more exercises above IAT than the more skilled dancers.

Examination of reptilian erythrocytes as models of the progenitor of mammalian red blood cells.

PubMed

Mauro, N A; Isaacks, R E

1997-04-01

Among the reptile species examined, only loggerhead turtle RBC with their high capacity of anaerobic metabolism and low oxygen uptake possess all the suitable metabolic characteristics as a model for transition from aerobic to anaerobic metabolism of mammalian erythrocytes (RBC). Neither the alligator RBC, which lack a significant level of anaerobic metabolism, nor the savannah monitor lizard RBC with their higher level of temperature-dependent aerobic metabolism, possess all the characteristics suitable as a model for the metabolic evolution of mammalian RBC. In the formation of this metabolic model, no phylogenetic relationships are implied or inferred. The metabolic similarity of loggerhead turtle RBC to mammalian RBC is further indicated by the high activity of the pentose phosphate (PPO4) pathway, as evidenced by the low thermal sensitivity of their oxygen uptake and by their low 14C6O2/14C1O2 ratios. By comparison, although the 14C6O2/14C1O2 ratios of both alligator and monitor lizard RBC are low as compared to loggerhead turtle RBC, only alligator RBC share with loggerhead turtle RBC a low thermal sensitivity of their oxygen uptake. A comparison of hemoglobin concentrations relative to hematocrit for loggerhead turtle, alligator and monitor lizard RBC indicates that RBC hemoglobin concentrations are approximately the same for each of these species. Apart from this similarity, RBC from these three species of reptiles were differentiated in this study with respect to their density and osmotic fragility.

Multifunctional Micelles Dually Responsive to Hypoxia and Singlet Oxygen: Enhanced Photodynamic Therapy via Interactively Triggered Photosensitizer Delivery.

PubMed

Li, Juanjuan; Meng, Xuan; Deng, Jian; Lu, Di; Zhang, Xin; Chen, Yanrui; Zhu, Jundong; Fan, Aiping; Ding, Dan; Kong, Deling; Wang, Zheng; Zhao, Yanjun

2018-05-23

Nanoparticulate antitumor photodynamic therapy (PDT) has been suffering from the limited dose accumulation in tumor. Herein, we report dually hypoxia- and singlet oxygen-responsive polymeric micelles to efficiently utilize the photosensitizer deposited in the disease site and hence facilely improve PDT's antitumor efficacy. Tailored methoxy poly(ethylene glycol)-azobenzene-poly(aspartic acid) copolymer conjugate with imidazole as the side chains was synthesized. The conjugate micelles (189 ± 19 nm) obtained by self-assembly could efficiently load a model photosensitizer, chlorin e6 (Ce6) with a loading of 4.1 ± 0.5% (w/w). The facilitated cellular uptake of micelles was achieved by the triggered azobenzene collapse that provoked poly(ethylene glycol) shedding; rapid Ce6 release was enabled by imidazole oxidation that induced micelle disassembly. In addition, the singlet oxygen-mediated cargo release not only addressed the limited diffusion range and short half-life of singlet oxygen but also decreased the oxygen level, which could in turn enhance internalization and increase the intracellular Ce6 concentration. The hypoxia-induced dePEGylation and singlet oxygen-triggered Ce6 release was demonstrated both in aqueous buffer and in Lewis lung carcinoma (LLC) cells. The cellular uptake study demonstrated that the dually responsive micelles could deliver significantly more Ce6 to the cells, which resulted in a substantially improved cytotoxicity. This concurred well with the superior in vivo antitumor ability of micelles in a LLC tumor-bearing mouse model. This study presented an intriguing nanoplatform to realize interactively triggered photosensitizer delivery and improved antitumor PDT efficacy.

Detection of phosphohydrolytic enzyme activity through the oxygen isotope composition of dissolved phosphate

NASA Astrophysics Data System (ADS)

Colman, A. S.

2016-02-01

Phosphohydrolytic enzymes play an important role in phosphorus remineralization. As they release phosphate (Pi) from various organophosphorus compounds, these enzymes facilitate the transfer of oxygen atoms from water to the phosphoryl moieties. Most such enzymatic reactions impart a significant isotopic fractionation to the oxygen transferred. If this reaction occurs within a cell, then the resultant oxygen isotope signal is overprinted by continued recycling of the Pi. However, if this reaction occurs extracellularly, then the isotopic signal will be preserved until the Pi is transported back into a cell. Thus, the oxygen isotope composition of Pi (δ18Op) in an aquatic ecosystem can serve as a useful indicator of the mechanisms by which P is remineralized. We develop a time-dependent model illustrating the sensitivity of the δ18O of dissolved phosphate to various modes of P remineralization. The model is informed by cell lysis experiments that reveal the relative proportions of P­i that are directly liberated from cytosol vs. regenerated from co-liberated dissolved organic phosphorus compounds via extracellular hydrolysis. By incorporating both cellular uptake and release fluxes of P, we show that the degree of isotopic disequilibrium in an aquatic ecosystem can be a strong indicator of P remineralization mode. Apparent oxygen isotope equilibrium between Pi and water arises in this model as a steady-state scenario in which fractionation upon cellular uptake of Pi counterbalances the hydrolytic source flux of disequilibrated Pi. Low and high rates of extracellular phosphohydrolase activity are shown to produce steady-state δ18Op values that are respectively above or below thermodynamic equilibrium compositions.

Oxygen Consumption of Elite Distance Runners on an Anti-Gravity Treadmill®

PubMed Central

McNeill, David K.P.; Kline, John R.; de Heer, Hendrick D.; Coast, J. Richard

2015-01-01

Lower body positive pressure (LBPP), or ‘anti-gravity’ treadmills® have become increasingly popular among elite distance runners. However, to date, few studies have assessed the effect of body weight support (BWS) on the metabolic cost of running among elite runners. This study evaluated how BWS influenced the relationship between velocity and metabolic cost among 6 elite male distance runners. Participants ran three- 16 minute tests consisting of 4 stages of 4 minutes at 8, 7, 6 and 5 min·mile−1 pace (3.35, 3.84, 4.47 and 5.36 m·s−1), while maintaining an aerobic effort (Respiratory Exchange Ratio ≤1.00). One test was run on a regular treadmill, one on an anti-gravity treadmill with 40% BWS and one with 20% BWS being provided. Expired gas data were collected and regression equations used to determine and compare slopes. Significant decreases in oxygen uptake (V̇O2) were found with each increase in BWS (p < 0.001). At 20% BWS, the average decrease in net VO2 was greater than proportional (34%), while at 40% BWS, the average net reduction in VO2 was close to proportional (38%). Across velocities, the slope of the relationship between VO2 and velocity (ΔV̇O2/Δv) was steeper with less support. The slopes at both the 20% and 40% BWS conditions were similar, especially when compared to the regular treadmill. Variability in VO2 between athletes was much greater on the LBPP treadmill and was greater with increased levels of BWS. In this study we evaluated the effect of body weight support on V̇O2 among elite distance runners. We have shown that oxygen uptake decreased with support, but not in direct proportion to that support. Further, because of the high variability in oxygen uptake between athletes on the LBPP treadmill, prediction equations may not be reliable and other indicators (heart rate, perceived exertion or directly measured oxygen uptake) should be used to guide training intensity when training on the LBPP treadmill. Key points With increasing amounts of body weight-support (BWS), the slope of the relationship between velocity and oxygen consumption (ΔVO2/Δv) decreases significantly. This means the change in oxygen consumption (VO2) is significantly smaller over a given change in velocity at higher amounts of BWS. There is a non-linear decrease in VO2 with increasing BWS. As such, with each increment in the amount of BWS provided, the reduction in VO2 becomes increasingly smaller. This paper provides first of its kind data on the effects of BWS on the cost of running among highly trained, elite runners. The outcomes of this study are in line with previous findings among non-elite runners. PMID:25983582

Regulation of iron transport systems in Enterobacteriaceae in response to oxygen and iron availability.

PubMed

Carpenter, Chandra; Payne, Shelley M

2014-04-01

Iron is an essential nutrient for most bacteria. Depending on the oxygen available in the surrounding environment, iron is found in two distinct forms: ferrous (Fe(II)) or ferric (Fe(III)). Bacteria utilize different transport systems for the uptake of the two different forms of iron. In oxic growth conditions, iron is found in its insoluble, ferric form, and in anoxic growth conditions iron is found in its soluble, ferrous form. Enterobacteriaceae have adapted to transporting the two forms of iron by utilizing the global, oxygen-sensing regulators, ArcA and Fnr to regulate iron transport genes in response to oxygen. Copyright © 2014 Elsevier Inc. All rights reserved.

Oxygen-storage behavior and local structure in Ti-substituted YMnO3

NASA Astrophysics Data System (ADS)

Levin, I.; Krayzman, V.; Vanderah, T. A.; Tomczyk, M.; Wu, H.; Tucker, M. G.; Playford, H. Y.; Woicik, J. C.; Dennis, C. L.; Vilarinho, P. M.

2017-02-01

Hexagonal manganates RMnO3 (R=Y, Ho, Dy) have been recently shown to exhibit oxygen-storage capacities promising for three-way catalysts, air-separation, and related technologies. Here, we demonstrate that Ti substitution for Mn can be used to chemically tune the oxygen-breathing properties of these materials towards practical applications. Specifically, Y(Mn1-xTix)O3 solid solutions exhibit facile oxygen absorption/desorption via reversible Ti3+↔Ti4+ and Mn3+↔Mn4+ reactions already in ambient air at ≈400 °C and ≈250 °C, respectively. On cooling, the oxidation of both cations is accompanied by oxygen uptake yielding a formula YMn3+1-x-yMn4+yTi4+xO3+δ. The presence of Ti promotes the oxidation of Mn3+ to Mn4+, which is almost negligible for YMnO3 in air, thereby increasing the uptake of oxygen beyond that required for a given Ti4+ concentration. The reversibility of the redox reactions is limited by sluggish kinetics; however, the oxidation process continues, if slowly, even at room temperature. The extra oxygen atoms are accommodated by the large interstices within a triangular lattice formed by the [MnO5] trigonal bipyramids. According to bond distances from Rietveld refinements using the neutron diffraction data, the YMnO3 structure features under-bonded Mn and even more severely under-bonded oxygen atoms that form the trigonal bases of the [MnO5] bipyramids. The tensile bond strain around the 5-fold coordinated Mn site and the strong preference of Ti4+(and Mn4+) for higher coordination numbers likely provide driving forces for the oxidation reaction. Reverse Monte Carlo refinements of the local atomic displacements using neutron total scattering revealed how the excess oxygen atoms are accommodated in the structure by correlated local displacements of the host atoms. Large displacements of the under-bonded host oxygen atoms play a key part in this lattice-relaxation process, facilitating reversible exchange of significant amounts of oxygen with atmosphere.

Oxygen-storage behavior and local structure in Ti-substituted YMnO 3

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

Levin, I.; Krayzman, V.; Vanderah, T. A.

Hexagonal manganates RMnO3 (R=Y, Ho, Dy) have been recently shown to exhibit oxygen-storage capacities promising for three-way catalysts, air-separation, and related technologies. Here, we demonstrate that Ti substitution for Mn can be used to chemically tune the oxygen-breathing properties of these materials towards practical applications. Specifically, Y(Mn1-xTix)O3 solid solutions exhibit facile oxygen absorption/desorption via reversible Ti3+↔Ti4+ and Mn3+↔Mn4+ reactions already in ambient air at ≈400 °C and ≈250 °C, respectively. On cooling, the oxidation of both cations is accompanied by oxygen uptake yielding a formula YMn3+1-x-yMn4+yTi4+xO3+δ. The presence of Ti promotes the oxidation of Mn3+ to Mn4+, which is almostmore » negligible for YMnO3 in air, thereby increasing the uptake of oxygen beyond that required for a given Ti4+ concentration. The reversibility of the redox reactions is limited by sluggish kinetics; however, the oxidation process continues, if slowly, even at room temperature. The extra oxygen atoms are accommodated by the large interstices within a triangular lattice formed by the [MnO5] trigonal bipyramids. According to bond distances from Rietveld refinements using the neutron diffraction data, the YMnO3 structure features under-bonded Mn and even more severely under-bonded oxygen atoms that form the trigonal bases of the [MnO5] bipyramids. The tensile bond strain around the 5-fold coordinated Mn site and the strong preference of Ti4+(and Mn4+) for higher coordination numbers likely provide driving forces for the oxidation reaction. Reverse Monte Carlo refinements of the local atomic displacements using neutron total scattering revealed how the excess oxygen atoms are accommodated in the structure by correlated local displacements of the host atoms. Large displacements of the under-bonded host oxygen atoms play a key part in this lattice-relaxation process, facilitating reversible exchange of significant amounts of oxygen with atmosphere.« less

Chitosan-shelled oxygen-loaded nanodroplets abrogate hypoxia dysregulation of human keratinocyte gelatinases and inhibitors: New insights for chronic wound healing.

PubMed

Khadjavi, Amina; Magnetto, Chiara; Panariti, Alice; Argenziano, Monica; Gulino, Giulia Rossana; Rivolta, Ilaria; Cavalli, Roberta; Giribaldi, Giuliana; Guiot, Caterina; Prato, Mauro

2015-08-01

In chronic wounds, efficient epithelial tissue repair is hampered by hypoxia, and balances between the molecules involved in matrix turn-over such as matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are seriously impaired. Intriguingly, new oxygenating nanocarriers such as 2H,3H-decafluoropentane-based oxygen-loaded nanodroplets (OLNs) might effectively target chronic wounds. To investigate hypoxia and chitosan-shelled OLN effects on MMP/TIMP production by human keratinocytes. HaCaT cells were treated for 24h with 10% v/v OLNs both in normoxia or hypoxia. Cytotoxicity and cell viability were measured through biochemical assays; cellular uptake by confocal microscopy; and MMP and TIMP production by enzyme-linked immunosorbent assay or gelatin zymography. Normoxic HaCaT cells constitutively released MMP-2, MMP-9, TIMP-1 and TIMP-2. Hypoxia strongly impaired MMP/TIMP balances by reducing MMP-2, MMP-9, and TIMP-2, without affecting TIMP-1 release. After cellular uptake by keratinocytes, nontoxic OLNs abrogated all hypoxia effects on MMP/TIMP secretion, restoring physiological balances. OLN abilities were specifically dependent on time-sustained oxygen diffusion from OLN core. Chitosan-shelled OLNs effectively counteract hypoxia-dependent dysregulation of MMP/TIMP balances in human keratinocytes. Therefore, topical administration of exogenous oxygen, properly encapsulated in nanodroplet formulations, might be a promising adjuvant approach to promote healing processes in hypoxic wounds. Copyright © 2015 Elsevier Inc. All rights reserved.

Energetics of Table Tennis and Table Tennis-Specific Exercise Testing.

PubMed

Zagatto, Alessandro Moura; Leite, Jorge Vieira de Mello; Papoti, Marcelo; Beneke, Ralph

2016-11-01

To test the hypotheses that the metabolic profile of table tennis is dominantly aerobic, anaerobic energy is related to the accumulated duration and intensity of rallies, and activity and metabolic profile are interrelated with the individual fitness profile determined via table tennis-specific tests. Eleven male experienced table tennis players (22 ± 3 y, 77.6 ± 18.9 kg, 177.1 ± 8.1 cm) underwent 2 simulated table tennis matches to analyze aerobic (W OXID ) energy, anaerobic glycolytic (W BLC ) energy, and phosphocreatine breakdown (W PCr ); a table tennis-specific graded exercise test to measure ventilatory threshold and peak oxygen uptake; and an exhaustive supramaximal table tennis effort to determine maximal accumulated deficit of oxygen. W OXID , W BLC , and W PCr corresponded to 96.5% ± 1.7%, 1.0% ± 0.7%, and 2.5% ± 1.4%, respectively. W OXID was interrelated with rally duration (r = .81) and number of shots per rally (r = .77), whereas match intensity was correlated with WPCr (r = .62) and maximal accumulated oxygen deficit (r = .58). The metabolic profile of table tennis is predominantly aerobic and interrelated with the individual fitness profile determined via table tennis-specific tests. Table tennis-specific ventilatory threshold determines the average oxygen uptake and overall W OXID , whereas table tennis-specific maximal accumulated oxygen deficit indicates the ability to use and sustain slightly higher blood lactate concentration and W BLC during the match.

Regulation of Acetate Utilization by Monocarboxylate Transporter 1 (MCT1) in Hepatocellular Carcinoma (HCC).

PubMed

Jeon, Jeong Yong; Lee, Misu; Whang, Sang Hyun; Kim, Jung-Whan; Cho, Arthur; Yun, Mijin

2018-01-19

Altered energy metabolism is a biochemical fingerprint of cancer cells. Hepatocellular carcinoma (HCC) shows reciprocal [18F]fluorodeoxyglucose (FDG) and [11C]acetate uptake, as revealed by positron emission tomography/computed tomography (PET/CT). Previous studies have focused on the role of FDG uptake in cancer cells. In this study, we evaluated the mechanism and roles of [11C]acetate uptake in human HCCs and cell lines. The expression of monocarboxylate transporters (MCTs) was assessed to determine the transporters of [11C]acetate uptake in HCC cell lines and human HCCs with different [11C]acetate uptake. Using two representative cell lines with widely different [11C]acetate uptake (HepG2 for high uptake and Hep3B for low uptake), changes in [11C]acetate uptake were measured after treatment with an MCT1 inhibitor or MCT1-targeted siRNA. To verify the roles of MCT1 in cells, oxygen consumption rate and the amount of lipid synthesis were measured. HepG2 cells with high [11C]acetate uptake showed higher MCT1 expression than other HCC cell lines with low [11C]acetate uptake. MCT1 expression was elevated in human HCCs with high [11C]acetate uptake compared to those with low [11C]acetate uptake. After blocking MCT1 with AR-C155858 or MCT1 knockdown, [11C]acetate uptake in HepG2 cells was significantly reduced. Additionally, inhibition of MCT1 suppressed mitochondrial oxidative phosphorylation, lipid synthesis, and cellular proliferation in HCC cells with high [11C]acetate uptake. MCT1 may be a new therapeutic target for acetate-dependent HCCs with high [11C]acetate uptake, which can be selected by [11C]acetate PET/CT imaging in clinical practice.

Oxygen Uptake Responses to Submaximal Exercise Loads Do Not Change During Long-Duration Space Flight

NASA Technical Reports Server (NTRS)

Moore, Alan D., Jr.; Evetts, Simon N.; Feiveson, Alan H.; Lee, S. M. C.; McCleary, Frank A.; Platts, Steven H.; Ploutz-Snyder, Lori

2011-01-01

In previous publications we have reported that the heart rate (HR) responses to graded submaximal exercise tests are elevated during long-duration International Space Station (ISS) flights. Furthermore, the elevation in HR appears greater earlier, rather than later, during the missions. A potential confounder in the interpretation of HR results from graded exercise tests on ISS is that the cycle ergometer used (CEVIS) is vibration-isolated from the station structure. This feature causes the CEVIS assembly to sway slightly during its use and debriefing comments by some crewmembers indicate that there is a "learning curve" associated with CEVIS use. Therefore, one could not exclude the possibility that the elevated HRs experienced in the early stages of ISS missions were related to a lowered metabolic efficiency of CEVIS exercise that would raise the submaximal oxygen uptake (VO2) associated with graded exercise testing work rates.

Assessment of physiological demand in kitesurfing.

PubMed

Vercruyssen, F; Blin, N; L'huillier, D; Brisswalter, J

2009-01-01

To evaluate the physiological demands of kitesurfing, ten elite subjects performed an incremental running test on a 400-m track and a 30-min on-water crossing trial during a light crosswind (LW, 12-15 knots). Oxygen uptake (V(O)(2)) was estimated from the heart rate (HR) recorded during the crossing trial using the individual HR-V(O)(2) relationship determined during the incremental test. Blood lactate concentration [La(b)] was measured at rest and 3 min after the exercise completion. Mean HR and estimated V(O)(2) values represented, respectively 80.6 +/- 7.5% of maximal heart rate and 69.8 +/- 11.7% of maximal oxygen uptake for board speeds ranging from 15 to 17 knots. Low values for [La(b)] were observed at the end of crossing trial (2.1 +/- 1.2 mmol l(-1). This first analysis of kitesurfing suggests that the energy demand is mainly sustained by aerobic metabolism during a LW condition.

Plasma lactic dehydrogenase activities in men during bed rest with exercise training

NASA Technical Reports Server (NTRS)

Greenleaf, J. E.; Juhos, L. T.; Young, H. L.

1985-01-01

Peak oxygen uptake and the activity of lactic dehydrogenase (LDH-T) and its five isoenzymes were measured by spectrophotometer in seven men before, during, and after bed rest and exercise training. Exercise training consisted of isometric leg exercises of 250 kcal/hr for a period of one hour per day. It is found that LDH-T was reduced by 0.05 percent in all three regimens by day 10 of bed rest, and that the decrease occurred at different rates. The earliest reduction in LDH-T activity in the no-exercise regimen was associated with a decrease in peak oxygen uptake of 12.3 percent. It is concluded that isometric (aerobic) muscular strength training appear to maintain skeletal muscle integrity better during bed rest than isotonic exercise training. Reduced hydrostatic pressure during bed rest, however, ultimately counteracts the effects of both moderate isometric and isotonic exercise training, and may result in decreased LDH-T activity.

Improvement in exercise capacity and delayed anaerobic metabolism induced by far-infrared-emitting garments in active healthy subjects: A pilot study.

PubMed

Mantegazza, Valentina; Contini, Mauro; Botti, Maurizia; Ferri, Ada; Dotti, Francesca; Berardi, Pierluigi; Agostoni, Piergiuseppe

2018-01-01

Background Far-infrared-emitting garments have several biological properties including the capability to increase blood perfusion in irradiated tissues. Design The aim of the study was to evaluate whether far-infrared radiation increases exercise capacity and delays anaerobic metabolism in healthy subjects. Methods With a double-blind, crossover protocol, a maximal cardiopulmonary exercise test was performed in 20 volunteers, wearing far-infrared or common sport clothes, identical in texture and colour. Results Comparing far-infrared with placebo garments, higher oxygen uptake at peak of exercise and longer endurance time were observed (peak oxygen uptake 38.0 ± 8.9 vs. 36.2 ± 8.5 ml/kg/min, endurance time 592 ± 85 vs. 570 ± 71 seconds; P < 0.01); the anaerobic threshold was significantly delayed (anaerobic threshold time 461 ± 93 vs. 417 ± 103 seconds) and anaerobic threshold oxygen uptake and anaerobic threshold oxygen pulse were significantly higher (25.3 ± 6.4 vs. 20.9 ± 5.4 ml/kg/min and 13.3 ± 3.8 vs. 12.4 ± 3.3 ml/beat, respectively). In 10 subjects the blood lactate concentration was measured every 2 minutes during exercise and at peak; lower values were observed with far-infrared fabrics compared to placebo from the eighth minute of exercise, reaching a significant difference at 10 minutes (3.6 ± 0.83 vs. 4.4 ± 0.96 mmol/l; P = 0.02). Conclusions In healthy subjects, exercising with a far-infrared outfit is associated with an improvement in exercise performance and a delay in anaerobic metabolism. In consideration of the acknowledged non-thermic properties of functionalised clothes, these effects could be mediated by an increase in oxygen peripheral delivery secondary to muscular vasodilation. These data suggest the need for testing far-infrared-emitting garments in patients with exercise limitation or in chronic cardiovascular and respiratory patients engaged in rehabilitation programmes.

New insights on the regulation of the adenine nucleotide pool of erythrocytes in mouse models

PubMed Central

O’Brien, William G.; Ling, Han Shawn; Lee, Cheng Chi

2017-01-01

The observation that induced torpor in non-hibernating mammals could result from an increased AMP concentration in circulation led our investigation to reveal that the added AMP altered oxygen transport of erythrocytes. To further study the effect of AMP in regulation of erythrocyte function and systemic metabolism, we generated mouse models deficient in key erythrocyte enzymes in AMP metabolism. We have previously reported altered erythrocyte adenine nucleotide levels corresponding to altered oxygen saturation in mice deficient in both CD73 and AMPD3. Here we further investigate how these Ampd3-/-/Cd73-/- mice respond to the administered dose of AMP in comparison with the control models of single enzyme deficiency and wild type. We found that Ampd3-/-/Cd73-/- mice are more sensitive to AMP-induced hypometabolism than mice with a single enzyme deficiency, which are more sensitive than wild type. A dose-dependent rightward shift of erythrocyte p50 values in response to increasing amounts of extracellular AMP was observed. We provide further evidence for the direct uptake of AMP by erythrocytes that is insensitive to dipyridamole, a blocker for ENT1. The uptake of AMP by the erythrocytes remained linear at the highest concentration tested, 10mM. We also observed competitive inhibition of AMP uptake by ATP and ADP but not by the other nucleotides and metabolites tested. Importantly, our studies suggest that AMP uptake is associated with an erythrocyte ATP release that is partially sensitive to inhibition by TRO19622 and Ca++ ion. Taken together, our study suggests a novel mechanism by which erythrocytes recycle and maintain their adenine nucleotide pool through AMP uptake and ATP release. PMID:28746349

New insights on the regulation of the adenine nucleotide pool of erythrocytes in mouse models.

PubMed

O'Brien, William G; Ling, Han Shawn; Zhao, Zhaoyang; Lee, Cheng Chi

2017-01-01

The observation that induced torpor in non-hibernating mammals could result from an increased AMP concentration in circulation led our investigation to reveal that the added AMP altered oxygen transport of erythrocytes. To further study the effect of AMP in regulation of erythrocyte function and systemic metabolism, we generated mouse models deficient in key erythrocyte enzymes in AMP metabolism. We have previously reported altered erythrocyte adenine nucleotide levels corresponding to altered oxygen saturation in mice deficient in both CD73 and AMPD3. Here we further investigate how these Ampd3-/-/Cd73-/- mice respond to the administered dose of AMP in comparison with the control models of single enzyme deficiency and wild type. We found that Ampd3-/-/Cd73-/- mice are more sensitive to AMP-induced hypometabolism than mice with a single enzyme deficiency, which are more sensitive than wild type. A dose-dependent rightward shift of erythrocyte p50 values in response to increasing amounts of extracellular AMP was observed. We provide further evidence for the direct uptake of AMP by erythrocytes that is insensitive to dipyridamole, a blocker for ENT1. The uptake of AMP by the erythrocytes remained linear at the highest concentration tested, 10mM. We also observed competitive inhibition of AMP uptake by ATP and ADP but not by the other nucleotides and metabolites tested. Importantly, our studies suggest that AMP uptake is associated with an erythrocyte ATP release that is partially sensitive to inhibition by TRO19622 and Ca++ ion. Taken together, our study suggests a novel mechanism by which erythrocytes recycle and maintain their adenine nucleotide pool through AMP uptake and ATP release.

Cerebral utilization of glucose, ketone bodies and oxygen in starving infant rats and the effect of intrauterine growth retardation.

PubMed

Dahlquist, G

1976-10-01

Cerebral arteriovenous differences of acetoacetate, D-beta-hydroxybutyrate, glucose, lactate and oxygen and brain DNA content was measured at 20 days of age in intrauterine growth retarded (IUGR) rats and normal littermates after 48 and 72 h of starvation. Cerebral blood flow (CBF) was measured with labeled microspheres in other comparable groups of IUGR and control rats. CBF was similar in IUGR and normal littermates (0.57+/-0.09 and 0.58+/-0.10 ml/min respectively). After 48 h of starvation, arterial glucose was significantly lower in IUGR than control animals but the arterial concentrations of ketone bodies were similar. After 48 h of starvation, cerebral arteriovenous difference of beta-hydroxybutyrate was significantly higher in control than IUGR rats also when expressed per mg brain DNA as was the fractional uptake of D-beta-hydroxybutyrate. After 72 h of starvation, arterial concentrations of ketone bodies were significantly lower in IUGR rats than controls but the fractional uptake of D-beta-hydroxybutyrate was increased compared to IUGR rats starved for 48 h. The average percentage of calculated total substrate uptake (mumol/min) accounted for by ketone bodies increased in control animals from 31.1% after 48 h of starvation to 41.0% after 72 h of starvation. In IUGR rats these percentage values were 26.5 and 25.7 respectively. After 72 h of starvation the fraction of total cerebral uptake of substrates accounted for by ketone bodies was significantly higher in control that IUGR rats. As total cerebral uptake of substrates was similar between IUGR and control animals it is concluded that IUGR rats are more dependent on glucose as a substrate for the brain during starvation.

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

Calo, J.M.; Suuberg, E.M.; Hradil, G.

This project is concerned with the study of the nature and behavior of ''active sites'' in char gasification. The research strategy involves use of model chars produced from the phenol-formaldehyde family of resins. These materials have been chosen since they have structural features similar to those in coals, but are much ''cleaner'' in that the concentration of potentially catalytic impurities can be maintained at low levels. It should be borne in mind that the objective of this work is to study non-catalytic gasification processes. In the previous quarterly report, we presented evidence that low temperature oxygen chemisorption does not providemore » a site-specific titration of active sites in chars; the uptake of oxygen by a cleaned char surface was unquestionably shown to be a function of temperature and oxygen partial pressure, and the importance of these variables differs from char to char. The fact that ''active surface area'' (ASA) determined by various arbitrary methods does seem to generally correlate with reactivity, seems to suggest that reactivities under various gasification and chemisorption conditions are correlated but that mechanisitic inferences cannot necessarily be drawn from such data. In the present report, we have extended the study of low temperature oxidation of chars, considering mass loss as well as oxygen uptake, since the two processes are essentially inseparable under a wide range of conditions. This work represents more than a simple attempt at trying to learn more about the oxygen chemisorption technique; rather it offers the opportunity to study the mechanism of oxygen attack on char under conditions that allow for better understanding of the fundamental processes. For these reasons, this work was performed in the pyrogasifier reactor (developed for CO/sub 2/ gasification reactivity studies), and complements the ongoing work in the TGA apparatus. 6 refs., 9 figs., 1 tab.« less

A Role of Erythrocytes in Adenosine Monophosphate Initiation of Hypometabolism in Mammals*

PubMed Central

Daniels, Isadora Susan; Zhang, Jianfa; O'Brien, William G.; Tao, Zhenyin; Miki, Tomoko; Zhao, Zhaoyang; Blackburn, Michael R.; Lee, Cheng Chi

2010-01-01

Biochemical and mechanistic aspects into how various hypometabolic states are initiated in mammals are poorly understood. Here, we show how a state of hypometabolism is initiated by 5′-AMP uptake by erythrocytes. Wild type, ecto-5′-nucleotidase-deficient, and adenosine receptor-deficient mice undergo 5′-AMP-induced hypometabolism in a similar fashion. Injection of 5′-AMP leads to two distinct declining phases of oxygen consumption (VO2). The phase I response displays a rapid and steep decline in VO2 that is independent of body temperature (Tb) and ambient temperature (Ta). It is followed by a phase II decline that is linked to Tb and moderated by Ta. Altering the dosages of 5′-AMP from 0.25- to 2-fold does not change the phase I response. For mice, a Ta of 15 °C is effective for induction of DH with the appropriate dose of 5′-AMP. Erythrocyte uptake of 5′-AMP leads to utilization of ATP to synthesize ADP. This is accompanied by increased glucose but decreased lactate levels, suggesting that glycolysis has slowed. Reduction in glycolysis is known to stimulate erythrocytes to increase intracellular levels of 2,3-bisphosphoglycerate, a potent allosteric inhibitor of hemoglobin's affinity for oxygen. Our studies showed that both 2,3-bisphosphoglycerate and deoxyhemoglobin levels rose following 5′-AMP administration and is in parallel with the phase I decline in VO2. In summary, our investigations reveal that 5′-AMP mediated hypometabolism is probably triggered by reduced oxygen transport by erythrocytes initiated by uptake of 5′-AMP. PMID:20430891

A role of erythrocytes in adenosine monophosphate initiation of hypometabolism in mammals.

PubMed

Daniels, Isadora Susan; Zhang, Jianfa; O'Brien, William G; Tao, Zhenyin; Miki, Tomoko; Zhao, Zhaoyang; Blackburn, Michael R; Lee, Cheng Chi

2010-07-02

Biochemical and mechanistic aspects into how various hypometabolic states are initiated in mammals are poorly understood. Here, we show how a state of hypometabolism is initiated by 5'-AMP uptake by erythrocytes. Wild type, ecto-5'-nucleotidase-deficient, and adenosine receptor-deficient mice undergo 5'-AMP-induced hypometabolism in a similar fashion. Injection of 5'-AMP leads to two distinct declining phases of oxygen consumption (VO(2)). The phase I response displays a rapid and steep decline in VO(2) that is independent of body temperature (T(b)) and ambient temperature (T(a)). It is followed by a phase II decline that is linked to T(b) and moderated by T(a). Altering the dosages of 5'-AMP from 0.25- to 2-fold does not change the phase I response. For mice, a T(a) of 15 degrees C is effective for induction of DH with the appropriate dose of 5'-AMP. Erythrocyte uptake of 5'-AMP leads to utilization of ATP to synthesize ADP. This is accompanied by increased glucose but decreased lactate levels, suggesting that glycolysis has slowed. Reduction in glycolysis is known to stimulate erythrocytes to increase intracellular levels of 2,3-bisphosphoglycerate, a potent allosteric inhibitor of hemoglobin's affinity for oxygen. Our studies showed that both 2,3-bisphosphoglycerate and deoxyhemoglobin levels rose following 5'-AMP administration and is in parallel with the phase I decline in VO(2). In summary, our investigations reveal that 5'-AMP mediated hypometabolism is probably triggered by reduced oxygen transport by erythrocytes initiated by uptake of 5'-AMP.

Functional High-Intensity Circuit Training Improves Body Composition, Peak Oxygen Uptake, Strength, and Alters Certain Dimensions of Quality of Life in Overweight Women.

PubMed

Sperlich, Billy; Wallmann-Sperlich, Birgit; Zinner, Christoph; Von Stauffenberg, Valerie; Losert, Helena; Holmberg, Hans-Christer

2017-01-01

The effects of circuit-like functional high-intensity training (Circuit HIIT ) alone or in combination with high-volume low-intensity exercise (Circuit combined ) on selected cardio-respiratory and metabolic parameters, body composition, functional strength and the quality of life of overweight women were compared. In this single-center, two-armed randomized, controlled study, overweight women performed 9-weeks (3 sessions·wk -1 ) of either Circuit HIIT ( n = 11), or Circuit combined ( n = 8). Peak oxygen uptake and perception of physical pain were increased to a greater extent ( p < 0.05) by Circuit HIIT , whereas Circuit combined improved perception of general health more ( p < 0.05). Both interventions lowered body mass, body-mass-index, waist-to-hip ratio, fat mass, and enhanced fat-free mass; decreased ratings of perceived exertion during submaximal treadmill running; improved the numbers of push-ups, burpees, one-legged squats, and 30-s skipping performed, as well as the height of counter-movement jumps; and improved physical and social functioning, role of physical limitations, vitality, role of emotional limitations, and mental health to a similar extent (all p < 0.05). Either forms of these multi-stimulating, circuit-like, multiple-joint training can be employed to improve body composition, selected variables of functional strength, and certain dimensions of quality of life in overweight women. However, Circuit HIIT improves peak oxygen uptake to a greater extent, but with more perception of pain, whereas Circuit combined results in better perception of general health.

Peak oxygen uptake and left ventricular ejection fraction, but not depressive symptoms, are associated with cognitive impairment in patients with chronic heart failure.

PubMed

Steinberg, Gerrit; Lossnitzer, Nicole; Schellberg, Dieter; Mueller-Tasch, Thomas; Krueger, Carsten; Haass, Markus; Ladwig, Karl Heinz; Herzog, Wolfgang; Juenger, Jana

2011-01-01

The aim of the present study was to assess cognitive impairment in patients with chronic heart failure (CHF) and its associations with depressive symptoms and somatic indicators of illness severity, which is a matter of controversy. Fifty-five patients with CHF (mean age 55.3 ± 7.8 years; 80% male; New York Heart Association functional class I-III) underwent assessment with an expanded neuropsychological test battery (eg, memory, complex attention, mental flexibility, psychomotor speed) to evaluate objective and subjective cognitive impairment. Depressive symptoms were assessed using the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (SCID) and a self-report inventory (Hospital Anxiety and Depression Scale [HADS]). A comprehensive clinical dataset, including left ventricular ejection fraction, peak oxygen uptake, and a 6-minute walk test, was obtained for all patients. Neuropsychological functioning revealed impairment in 56% of patients in at least one measure of our neuropsychological test battery. However, the Mini Mental State Examination (MMSE) could only detect cognitive impairment in 1.8% of all patients, 24% had HADS scores indicating depressive symptoms, and 11.1% met SCID criteria for a depressive disorder. No significant association was found between depressive symptoms and cognitive impairment. Left ventricular ejection fraction was related to subjective cognitive impairment, and peak oxygen uptake was related to objective cognitive impairment. Cognitive functioning was substantially reduced in patients with CHF and should therefore be diagnosed and treated in routine clinical practice. Caution is advised when the MMSE is used to identify cognitive impairment in patients with CHF.

Importance of Non-invasive Right and Left Ventricular Variables on Exercise Capacity in Patients with Tetralogy of Fallot Hemodynamics.

PubMed

Meierhofer, Christian; Tavakkoli, Timon; Kühn, Andreas; Ulm, Kurt; Hager, Alfred; Müller, Jan; Martinoff, Stefan; Ewert, Peter; Stern, Heiko

2017-12-01

Good quality of life correlates with a good exercise capacity in daily life in patients with tetralogy of Fallot (ToF). Patients after correction of ToF usually develop residual defects such as pulmonary regurgitation or stenosis of variable severity. However, the importance of different hemodynamic parameters and their impact on exercise capacity is unclear. We investigated several hemodynamic parameters measured by cardiovascular magnetic resonance (CMR) and echocardiography and evaluated which parameter has the most pronounced effect on maximal exercise capacity determined by cardiopulmonary exercise testing (CPET). 132 patients with ToF-like hemodynamics were tested during routine follow-up with CMR, echocardiography and CPET. Right and left ventricular volume data, ventricular ejection fraction and pulmonary regurgitation were evaluated by CMR. Echocardiographic pressure gradients in the right ventricular outflow tract and through the tricuspid valve were measured. All data were classified and correlated with the results of CPET evaluations of these patients. The analysis was performed using the Random Forest model. In this way, we calculated the importance of the different hemodynamic variables related to the maximal oxygen uptake in CPET (VO 2 %predicted). Right ventricular pressure showed the most important influence on maximal oxygen uptake, whereas pulmonary regurgitation and right ventricular enddiastolic volume were not important hemodynamic variables to predict maximal oxygen uptake in CPET. Maximal exercise capacity was only very weakly influenced by right ventricular enddiastolic volume and not at all by pulmonary regurgitation in patients with ToF. The variable with the most pronounced influence was the right ventricular pressure.

Sex differences in performance-matched marathon runners.

PubMed

Helgerud, J; Ingjer, F; Strømme, S B

1990-01-01

Six male and six female runners were chosen on the basis of age (20-30 years) and their performance over the marathon distance (mean time = 199.4, SEM 2.3 min for men and 201.8, SEM 1.8 min for women). The purpose was to find possible sex differences in maximal aerobic power (VO2max), anaerobic threshold, running economy, degree and utilization of VO2max (when running a marathon) and amount of training. The results showed that performance-matched male and female marathon runners had approximately the same VO2max (about 60 ml.kg-1.min-1). For both sexes the anaerobic threshold was reached at an exercise intensity of about 83% of VO2max, or 88%-90% of maximal heart rate. The females' running economy was poorer, i.e. their oxygen uptake during running at a standard submaximal speed was higher (P less than 0.05). The heart rate, respiratory exchange ratio and blood lactate concentration also confirmed that a given running speed resulted in higher physiological strain for the females. The percentage utilization of VO2max at the average marathon running speed was somewhat higher for the females, but the difference was not significant. For both sexes the oxygen uptake at average speed was 93%-94% of the oxygen uptake corresponding to the anaerobic threshold. Answers to a questionnaire showed that the females' training programme over the last 2 months prior to running the actual marathon comprised almost twice as many kilometers of running per week compared to the males (60 and 33 km, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Functional High-Intensity Circuit Training Improves Body Composition, Peak Oxygen Uptake, Strength, and Alters Certain Dimensions of Quality of Life in Overweight Women

PubMed Central

Sperlich, Billy; Wallmann-Sperlich, Birgit; Zinner, Christoph; Von Stauffenberg, Valerie; Losert, Helena; Holmberg, Hans-Christer

2017-01-01

The effects of circuit-like functional high-intensity training (CircuitHIIT) alone or in combination with high-volume low-intensity exercise (Circuitcombined) on selected cardio-respiratory and metabolic parameters, body composition, functional strength and the quality of life of overweight women were compared. In this single-center, two-armed randomized, controlled study, overweight women performed 9-weeks (3 sessions·wk−1) of either CircuitHIIT (n = 11), or Circuitcombined (n = 8). Peak oxygen uptake and perception of physical pain were increased to a greater extent (p < 0.05) by CircuitHIIT, whereas Circuitcombined improved perception of general health more (p < 0.05). Both interventions lowered body mass, body-mass-index, waist-to-hip ratio, fat mass, and enhanced fat-free mass; decreased ratings of perceived exertion during submaximal treadmill running; improved the numbers of push-ups, burpees, one-legged squats, and 30-s skipping performed, as well as the height of counter-movement jumps; and improved physical and social functioning, role of physical limitations, vitality, role of emotional limitations, and mental health to a similar extent (all p < 0.05). Either forms of these multi-stimulating, circuit-like, multiple-joint training can be employed to improve body composition, selected variables of functional strength, and certain dimensions of quality of life in overweight women. However, CircuitHIIT improves peak oxygen uptake to a greater extent, but with more perception of pain, whereas Circuitcombined results in better perception of general health. PMID:28420999

Preferential reduction of quadriceps over respiratory muscle strength and bulk after lung transplantation for cystic fibrosis.

PubMed

Pinet, C; Scillia, P; Cassart, M; Lamotte, M; Knoop, C; Mélot, C; Estenne, M

2004-09-01

In the absence of complications, recipients of lung transplants for cystic fibrosis have normal pulmonary function but the impact of the procedure on the strength and bulk of respiratory and limb muscles has not been studied. Twelve stable patients who had undergone lung transplantation for cystic fibrosis 48 months earlier (range 8-95) and 12 normal subjects matched for age, height, and sex were studied. The following parameters were measured: standard lung function, peak oxygen uptake by cycle ergometry, diaphragm surface area by computed tomographic (CT) scanning, diaphragm and abdominal muscle thickness by ultrasonography, twitch transdiaphragmatic and gastric pressures, quadriceps isokinetic strength, and quadriceps cross section by CT scanning, and lean body mass. Diaphragm mass was computed from diaphragm surface area and thickness. Twitch transdiaphragmatic and gastric pressures, diaphragm mass, and abdominal muscle thickness were similar in the two groups but quadriceps strength and cross section were decreased by nearly 30% in the patients. Patients had preserved quadriceps strength per unit cross section but reduced quadriceps cross section per unit lean body mass. The cumulative dose of corticosteroids was an independent predictor of quadriceps atrophy. Peak oxygen uptake showed positive correlations with quadriceps strength and cross section in the two groups, but peak oxygen uptake per unit quadriceps strength or cross section was reduced in the patient group. The diaphragm and abdominal muscles have preserved strength and bulk in patients transplanted for cystic fibrosis but the quadriceps is weak due to muscle atrophy. This atrophy is caused in part by corticosteroid therapy and correlates with the reduction in exercise capacity.

Microoxic Niches within the Thylakoid Stroma of Air-Grown Chlamydomonas reinhardtii Protect [FeFe]-Hydrogenase and Support Hydrogen Production under Fully Aerobic Environment1[OPEN

PubMed Central

Liran, Oded; Milrad, Yuval; Eilenberg, Haviva; Weiner, Iddo

2016-01-01

Photosynthetic hydrogen production in the microalga Chlamydomonas reinhardtii is catalyzed by two [FeFe]-hydrogenase isoforms, HydA1 and HydA2, both irreversibly inactivated upon a few seconds exposure to atmospheric oxygen. Until recently, it was thought that hydrogenase is not active in air-grown microalgal cells. In contrast, we show that the entire pool of cellular [FeFe]-hydrogenase remains active in air-grown cells due to efficient scavenging of oxygen. Using membrane inlet mass spectrometry, 18O2 isotope, and various inhibitors, we were able to dissect the various oxygen uptake mechanisms. We found that both chlororespiration, catalyzed by plastid terminal oxidase, and Mehler reactions, catalyzed by photosystem I and Flavodiiron proteins, significantly contribute to oxygen uptake rate. This rate is considerably enhanced with increasing light, thus forming local anaerobic niches at the proximity of the stromal face of the thylakoid membrane. Furthermore, we found that in transition to high light, the hydrogen production rate is significantly enhanced for a short duration (100 s), thus indicating that [FeFe]-hydrogenase functions as an immediate sink for surplus electrons in aerobic as well as in anaerobic environments. In summary, we show that an anaerobic locality in the chloroplast preserves [FeFe]-hydrogenase activity and supports continuous hydrogen production in air-grown microalgal cells. PMID:27443604

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

PubMed

Paixão, S M; Anselmo, A M

2002-01-01

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

Effects of Systematic Variation in Size and Surface Coating of Silver Nanoparticles on Their In Vitro Toxicity to Macrophage RAW 264.7 Cells.

PubMed

Makama, Sunday; Kloet, Samantha K; Piella, Jordi; van den Berg, Hans; de Ruijter, Norbert C A; Puntes, Victor F; Rietjens, Ivonne M C M; van den Brink, Nico W

2018-03-01

In literature, varying and sometimes conflicting effects of physicochemical properties of nanoparticles (NPs) are reported on their uptake and effects in organisms. To address this, small- and medium-sized (20 and 50 nm) silver nanoparticles (AgNPs) with specified different surface coating/charges were synthesized and used to systematically assess effects of NP-properties on their uptake and effects in vitro. Silver nanoparticles were fully characterized for charge and size distribution in both water and test media. Macrophage cells (RAW 264.7) were exposed to these AgNPs at different concentrations (0-200 µg/ml). Uptake dynamics, cell viability, induction of tumor necrosis factor (TNF)-α, ATP production, and reactive oxygen species (ROS) generation were assessed. Microscopic imaging of living exposed cells showed rapid uptake and subcellular cytoplasmic accumulation of AgNPs. Exposure to the tested AgNPs resulted in reduced overall viability. Influence of both size and surface coating (charge) was demonstrated, with the 20-nm-sized AgNPs and bovine serum albumin (BSA)-coated (negatively charged) AgNPs being slightly more toxic. On specific mechanisms of toxicity (TNF-α and ROS production) however, the AgNPs differed to a larger extent. The highest induction of TNF-α was found in cells exposed to the negatively charged AgNP_BSA, both sizes (80× higher than control). Reactive oxygen species induction was only significant with the 20 nm positively charged AgNP_Chit.

Activated Sludge.

ERIC Educational Resources Information Center

Saunders, F. Michael

1978-01-01

Presents the 1978 literature review of wastewater treatment. This review covers: (1) activated sludge process; (2) process control; (3) oxygen uptake and transfer; (4) phosphorus removal; (5) nitrification; (6) industrial wastewater; and (7) aerobic digestion. A list of 136 references is also presented. (HM)

Central Circulatory Adaptations to Physical Training

ERIC Educational Resources Information Center

Van Handel, Peter J.; And Others

1976-01-01

A ten-week jogging program for middle-aged people can reduce heart rate during the performance of tasks other than running; it appears that tissue adaptations for uptake and use of oxygen may influence the cardiovascular response to exercise. (JD)

Updating the Skating Multistage Aerobic Test and Correction for V[Combining Dot Above]O2max Prediction Using a New Skating Economy Index in Elite Youth Ice Hockey Players.

PubMed

Allisse, Maxime; Bui, Hung Tien; Léger, Luc; Comtois, Alain-Steve; Leone, Mario

2018-05-07

Allisse, M, Bui, HT, Léger, L, Comtois, A-S, and Leone, M. Updating the skating multistage aerobic test and correction for V[Combining Dot Above]O2max prediction using a new skating economy index in elite youth ice hockey players. J Strength Cond Res XX(X): 000-000, 2018-A number of field tests, including the skating multistage aerobic test (SMAT), have been developed to predict V[Combining Dot Above]O2max in ice hockey players. The SMAT, like most field tests, assumes that participants who reach a given stage have the same oxygen uptake, which is not usually true. Thus, the objectives of this research are to update the V[Combining Dot Above]O2 values during the SMAT using a portable breath-by-breath metabolic analyzer and to propose a simple index of skating economy to improve the prediction of oxygen uptake. Twenty-six elite hockey players (age 15.8 ± 1.3 years) participated in this study. The oxygen uptake was assessed using a portable metabolic analyzer (K4b) during an on-ice maximal shuttle skate test. To develop an index of skating economy called the skating stride index (SSI), the number of skating strides was compiled for each stage of the test. The SMAT enabled the prediction of the V[Combining Dot Above]O2max (ml·kg·min) from the maximal velocity (m·s) and the SSI (skating strides·kg) using the following regression equation: V[Combining Dot Above]O2max = (14.94 × maximal velocity) + (3.68 × SSI) - 24.98 (r = 0.95, SEE = 1.92). This research allowed for the update of the oxygen uptake values of the SMAT and proposed a simple measure of skating efficiency for a more accurate evaluation of V[Combining Dot Above]O2max in elite youth hockey players. By comparing the highest and lowest observed SSI scores in our sample, it was noted that the V[Combining Dot Above]O2 values can vary by up to 5 ml·kg·min. Our results suggest that skating economy should be included in the prediction of V[Combining Dot Above]O2max to improve prediction accuracy.

Sea-level haemoglobin concentration is associated with greater exercise capacity in Tibetan males at 4200 m.

PubMed

Wagner, P D; Simonson, T S; Wei, G; Wagner, H E; Wuren, T; Qin, G; Yan, M; Ge, R L

2015-11-01

What is the topic of this review? Recent developments link relatively lower hemoglobin concentration in Tibetans at high altitude to exercise capacity and components of oxygen transport. What advances does it highlight? Haemoglobin concentration (ranging from 15.2 to 22.9 g dl(-1) ) in Tibetan males was negatively associated with peak oxygen (O2 ) uptake per kilogram, cardiac output and muscle O2 diffusion conductance. Most variance in the peak O2 uptake per kilogram of Tibetan males was attributed to cardiac output, muscle diffusional conductance and arterial partial pressure of CO2 . The mechanisms underlying these differences in oxygen transport in Tibetans require additional analyses. Despite residence at >4000 m above sea level, many Tibetan highlanders, unlike Andean counterparts and lowlanders at altitude, exhibit haemoglobin concentration ([Hb]) within the typical sea-level range. Genetic adaptations in Tibetans are associated with this relatively low [Hb], yet the functional relevance of the lower [Hb] remains unknown. To address this, we examined each major step of the oxygen transport cascade [ventilation (VE), cardiac output (QT) and diffusional conductance in lung (DL) and muscle (DM)] in Tibetan males at maximal exercise on a cycle ergometer. Ranging from 15.2 to 22.9 g dl(-1) , [Hb] was negatively associated with peak O2 uptake per kilogram (r = -0.45, P < 0.05) and both cardiac output (QT/kg: r = -0.54, P < 0.02) and muscle O2 diffusion conductance (DM/kg: r = -0.44, P < 0.05) but not ventilation, arterial partial pressure of O2 or pulmonary diffusing capacity. Most variance in peak O2 uptake per kilogram was attributed to QT, DM and arterial partial pressure of CO2 (r(2)  = 0.90). In summary, lack of polycythaemia in Tibetans is associated with increased exercise capacity, which is explained by elevated cardiac, muscle and, to a small extent, ventilatory responses rather than pulmonary gas exchange. Whether lower [Hb] is the cause or result of these changes in O2 transport or is causally unrelated will require additional study. © 2015 The Authors. Experimental Physiology © 2015 The Physiological Society.

Uptake of phytodetritus by benthic foraminifera under oxygen depletion at the Indian margin (Arabian Sea)

NASA Astrophysics Data System (ADS)

Enge, A. J.; Witte, U.; Kucera, M.; Heinz, P.

2014-04-01

Benthic foraminifera in sediments on the Indian margin of the Arabian Sea, where the oxygen minimum zone (OMZ) impinges on the continental slope, are exposed to particularly severe levels of oxygen depletion. Food supply for the benthic community is high but delivered in distinct pulses during upwelling and water mixing events associated with summer and winter monsoon periods. In order to investigate the response by benthic foraminifera to such pulsed food delivery under oxygen concentrations of less than 0.1 mL L-1 (4.5 μmol L-1), an in situ isotope labeling experiment (13C, 15N) was performed on the western continental slope of India at 540 m water depth (OMZ core region). The assemblage of living foraminifera (>125 μm) in the uppermost centimeter at this depth is characterized by an unexpectedly high population density of 3982 individuals 10 cm-2 and a strong dominance by few calcareous species. For the experiment, we concentrated on the nine most abundant taxa, which constitute 93% of the entire foraminiferal population at 0-1 cm sediment depth. Increased concentrations of 13C and 15N in the cytoplasm indicate that all investigated taxa took up labeled phytodetritus during the 4 day experimental phase. In total, these nine species had assimilated 113.8 mg C m-2 (17.5% of the total added carbon). Uptake of nitrogen by the three most abundant taxa (Bolivina aff. B. dilatata, Cassidulina sp., Bulimina gibba) was 2.7 mg N m-2 (2% of the total added nitrogen). The response to the offered phytodetritus varied largely among foraminiferal species with Uvigerina schwageri being by far the most important species in short-term processing, whereas the most abundant taxa Bolivina aff. B. dilatata and Cassidulina sp. showed comparably low uptake of the offered food. We suggest the observed species-specific differences are related to species biomass and specific feeding preferences. In summary, the experiment in the OMZ core region shows rapid processing of fresh phytodetritus by foraminifera under almost anoxic conditions. The uptake of large amounts of organic matter by few species within four days suggests that foraminifera may play an important role in short-term carbon cycling in the OMZ core region on the Indian margin.

Effects of a high-intensity intermittent training program on aerobic capacity and lipid profile in trained subjects

PubMed Central

Ouerghi, Nejmeddine; Khammassi, Marwa; Boukorraa, Sami; Feki, Moncef; Kaabachi, Naziha; Bouassida, Anissa

2014-01-01

Background Data regarding the effect of training on plasma lipids are controversial. Most studies have addressed continuous or long intermittent training programs. The present study evaluated the effect of short-short high-intensity intermittent training (HIIT) on aerobic capacity and plasma lipids in soccer players. Methods The study included 24 male subjects aged 21–26 years, divided into three groups: experimental group 1 (EG1, n=8) comprising soccer players who exercised in addition to regular short-short HIIT twice a week for 12 weeks; experimental group 2 (EG2, n=8) comprising soccer players who exercised in a regular football training program; and a control group (CG, n=8) comprising untrained subjects who did not practice regular physical activity. Maximal aerobic velocity and maximal oxygen uptake along with plasma lipids were measured before and after 6 weeks and 12 weeks of the respective training program. Results Compared with basal values, maximal oxygen uptake had significantly increased in EG1 (from 53.3±4.0 mL/min/kg to 54.8±3.0 mL/min/kg at 6 weeks [P<0.05] and to 57.0±3.2 mL/min/kg at 12 weeks [P<0.001]). Maximal oxygen uptake was increased only after 12 weeks in EG2 (from 52.8±2.7 mL/min/kg to 54.2±2.6 mL/min/kg, [P<0.05]), but remain unchanged in CG. After 12 weeks of training, maximal oxygen uptake was significantly higher in EG1 than in EG2 (P<0.05). During training, no significant changes in plasma lipids occurred. However, after 12 weeks, total and low-density lipoprotein cholesterol levels had decreased (by about 2%) in EG1 but increased in CG. High-density lipoprotein cholesterol levels increased in EG1 and EG2, but decreased in CG. Plasma triglycerides decreased by 8% in EG1 and increased by about 4% in CG. Conclusion Twelve weeks of short-short HIIT improves aerobic capacity. Although changes in the lipid profile were not significant after this training program, they may have a beneficial impact on health. PMID:25378960

Relation of oxygen uptake to work rate in prepubertal healthy children - reference for VO2/W-slope and effect on cardiorespiratory fitness assessment.

PubMed

Tompuri, Tuomo; Lintu, Niina; Laitinen, Tomi; Lakka, Timo A

2017-08-09

Exercise testing by cycle ergometer allows to observe the interaction between oxygen uptake (VO 2 ) and workload (W), and VO 2 /W-slope can be used as a diagnostic tool. Respectively, peak oxygen uptake (VO 2 PEAK ) can be estimated by maximal workload. We aim to determine reference for VO 2 /W-slope among prepubertal children and define agreement between estimated and measured VO 2 PEAK . A total of 38 prepubertal children (20 girls) performed a maximal cycle ergometer test with respiratory gas analysis. VO 2 /W-slopes were computed using linear regression. Agreement analysis by Bland and Altman for estimated and measured VO 2 PEAK was carried out including limits of agreement (LA). Determinants for VO 2 /W-slopes and estimation bias were defined. VO2/W-slope was in both girls and boys ≥9·4 and did not change with exercise level, but the oxygen cost of exercise was higher among physically more active children. Estimated VO 2 PEAK had 6·4% coefficient of variation, and LA varied from 13% underestimation to 13% overestimation. Bias had a trend towards underestimation along lean mass proportional VO 2 PEAK . The primary determinant for estimation bias was VO2/W-slope (β = -0·65; P<0·001). The reference values for VO 2 /W-slope among healthy prepubertal children were similar to those published for adults and among adolescents. Estimated and measured VO 2 PEAK should not be considered to be interchangeable because of the variation in the relationship between VO 2 and W. On other hand, variation in the relationship between VO 2 and W enables that VO 2 /W-slope can be used as a diagnostic tool. © 2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Influence of CeO{sub 2} NPs on biological phosphorus removal and bacterial community shifts in a sequencing batch biofilm reactor with the differential effects of molecular oxygen

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

Xu, Yi; Wang, Chao

2016-11-15

The effects of CeO{sub 2} nanoparticles (CeO{sub 2} NPs) on a sequencing batch biofilm reactor (SBBR) with established biological phosphorus (P) removal were investigated from the processes of anaerobic P release and aerobic P uptake. At low concentration (0.1 mg/L), no significant impact was observed on total phosphorus (TP) removal after operating for 8 h. However, at a concentration of 20 mg/L, TP removal efficiency decreased from 83.68% to 55.88% and 16.76% when the CeO{sub 2} NPs were added at the beginning of the anaerobic and aerobic periods, respectively. Further studies illustrated that the inhibition of the specific P releasemore » rate was caused by the reversible states of Ce{sup 3+} and Ce{sup 4+}, which inhibited the activity of exopolyphosphatase (PPX) and transformation of poly-β-hydoxyalkanoates (PHA) and glycogen, as well as the uptake of volatile fatty acids (VFAs). The decrease in the specific P uptake rate was mainly attributed to the significantly suppressed energy generation and decreased abundance of Burkholderia caused by excess reactive oxygen species. The removal of chemical oxygen demand (COD) was not influenced by CeO{sub 2} NPs under aerobic conditions, due to the increased abundance of Acetobacter and Acidocella after exposure. The inhibitory effects of CeO{sub 2} NPs with molecular oxygen were reduced after anaerobic exposure due to the enhanced particle size and the presence of Ce{sup 3+}. - Highlights: • CeO{sub 2} NPs (20 mg/L) had a notable toxicity effect on P removal in SBBR system. • The deteriorated SPRR was caused by the inhibited key enzyme activity (PPX). • The decreased SPUR was caused by the bacterial community shifts. • Ce ions converting and excess ROS generation are related toxicity mechanisms.« less

Comparison of oxygen transfer parameters and oxygen demands in bioreactors operated at low and high dissolved oxygen levels.

PubMed

Mines, Richard O; Callier, Matthew C; Drabek, Benjamin J; Butler, André J

2017-03-21

The proper design of aeration systems for bioreactors is critical since it can represent up to 50% of the operational and capital cost at water reclamation facilities. Transferring the actual amount of oxygen needed to meet the oxygen demand of the wastewater requires α- and β-factors, which are used for calculating the actual oxygen transfer rate (AOTR) under process conditions based on the standard oxygen transfer rate (SOTR). The SOTR is measured in tap water at 20°C, 1 atmospheric pressure, and 0 mg L -1 of dissolved oxygen (DO). In this investigation, two 11.4-L bench-scale completely mixed activated process (CMAS) reactors were operated at various solid retention times (SRTs) to ascertain the relationship between the α-factor and SRT, and between the β-factor and SRT. The second goal was to determine if actual oxygen uptake rates (AOURs) are equal to calculated oxygen uptake rates (COURs) based on mass balances. Each reactor was supplied with 0.84 L m -1 of air resulting in SOTRs of 14.3 and 11.5 g O 2 d -1 for Reactor 1 (R-1) and Reactor 2 (R-2), respectively. The estimated theoretical oxygen demands of the synthetic feed to R-1 and R-2 were 6.3 and 21.9 g O 2 d -1 , respectively. R-2 was primarily operated under a dissolved oxygen (DO) limitation and high nitrogen loading to determine if nitrification would be inhibited from a nitrite buildup and if this would impact the α-factor. Nitrite accumulated in R-2 at DO concentrations ranging from 0.50 to 7.35 mg L -1 and at free ammonia (FA) concentrations ranging from 1.34 to 7.19 mg L -1 . Nonsteady-state reaeration tests performed on the effluent from each reactor and on tap water indicated that the α-factor increased as SRT increased. A simple statistical analysis (paired t-test) between AOURs and COURs indicated that there was a statistically significant difference at 0.05 level of significance for both reactors. The ex situ BOD bottle method for estimating AOUR appears to be invalid in bioreactors operated at low DO concentrations (<1.0 mg L -1 ).

Comparative amperometric study of uptake hydrogenase and hydrogen photoproduction activities between heterocystous cyanobacterium Anabaena cylindrica B629 and nonheterocystous cyanobacterium Oscillatoria sp. strain Miami BG7

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

Kumazawa, S.; Mitsui, A.

Heterocystous filamentous cyanobacterium Anabaena cylindrica B629 and nonheterocystous filamentous cyanobacterium Oscillatoria sp. strain Miami BG7 were cultured in media with N/sub 2/ as the sole nitrogen source; and activities of oxygen-dependent hydrogen uptake, photohydrogen production photooxygen evolution, and respiration were compared amperometrically under the same or similar experimental conditions for both strains. Distinct differences in these activities were observed in both strains. The rates of hydrogen photoproduction and hydrogen accumulation were significantly higher in Oscillatoria sp. strain BG7 than in A. cylindrica B629 at every light intensity tested. The major reason for the difference was attributable to the fact thatmore » the heterocystous cyanobacterium had a high rate of oxygen-dependent hydrogen consumption activity and the nonheterocystous cyanobacterium did not. The activity of oxygen photoevolution and respiration also contributed to the difference. Oscillatoria sp. strain BG7 had lower O/sub 2/ evolution and higher respiration than did A. cylindrica B629. Thus, the effect of O/sub 2/ on hydrogen photoproduction was minimized in Oscillatoria sp. strain BG7. 32 references, 5 figures.« less

Development, validity, and reliability of a ballet-specific aerobic fitness test.

PubMed

Twitchett, Emily; Nevill, Alan; Angioi, Manuela; Koutedakis, Yiannis; Wyon, Matthew

2011-09-01

The aim of this study was to develop and assess the reliability and validity of a multi-stage, ballet-specific aerobic fitness test to be used in a dance studio setting. The test consists of five stages, each four minutes long, that increase in intensity. It uses classical ballet movement of an intermediate-level of difficulty, thus emphasizing physiological demand rather than skill. The demand of each stage was determined by calculating the mean oxygen uptake during its final minute using a portable gas analyser. After an initial familiarization period, eight female subjects performed the test twice within seven days. The results showed significant differences in oxygen consumption between stages (p < 0.001), but not between trials. Pearson correlation co-efficients produced a very good linear relationship between trials (r = 0.998, p < 0.001). Bland-Altman reliability analysis revealed the 95% limits of agreement to be ± 6.2 ml·kg(-1)·min(-1), showing good agreement between trials. The oxygen uptake in our subjects equated positively to previous estimates for class and performance, confirming validity. It was concluded that the test is suitable for use among classical ballet dancers, with many possible applications.

[Adaptive specific features of energy metabolism in fish ontogenesis].

PubMed

Ozerniuk, N D

2011-01-01

A review of data on the pattern of change of the intensity of oxygen consumption during early ontogenesis of different fish species (rainbow trout, loach, zebrafish, carp, and grass carp) is provided. It has a similar pattern: this index increases in the period of embryonic and larval development and, after passing of larvae to an active feeding, it begins to gradually decline. This dynamics is determined by specific features of an increase in the rate of oxygen uptake and body weight in the course of early stages of fish ontogenesis. For determining optimal temperature conditions of development, a method of total (for a definite stage of development) oxygen uptake was suggested, which makes it possible to determine minimal energy expenditures necessary for the process of a particular stage of embryogenesis to take place. Analysis of temperature dependence of kinetic properties of enzymes with reference to the Michaelis constant (Km) for lactate dehydrogenase demonstrated that minimal Km, corresponding to maximal enzyme-substrate affinity, for embryos of different fish species differs in correspondence with differences in temperature conditions of development of these species in nature. For embryos of one species developing at changing temperature conditions (salmonids), this index changes in accordance with a temperature drift in nature.

Athero-inflammatory nanotherapeutics: Ferulic acid-based poly(anhydride-ester) nanoparticles attenuate foam cell formation by regulating macrophage lipogenesis and reactive oxygen species generation.

PubMed

Chmielowski, Rebecca A; Abdelhamid, Dalia S; Faig, Jonathan J; Petersen, Latrisha K; Gardner, Carol R; Uhrich, Kathryn E; Joseph, Laurie B; Moghe, Prabhas V

2017-07-15

Enhanced bioactive anti-oxidant formulations are critical for treatment of inflammatory diseases, such as atherosclerosis. A hallmark of early atherosclerosis is the uptake of oxidized low density lipoprotein (oxLDL) by macrophages, which results in foam cell and plaque formation in the arterial wall. The hypolipidemic, anti-inflammatory, and antioxidative properties of polyphenol compounds make them attractive targets for treatment of atherosclerosis. However, high concentrations of antioxidants can reverse their anti-atheroprotective properties and cause oxidative stress within the artery. Here, we designed a new class of nanoparticles with anti-oxidant polymer cores and shells comprised of scavenger receptor targeting amphiphilic macromolecules (AMs). Specifically, we designed ferulic acid-based poly(anhydride-ester) nanoparticles to counteract the uptake of high levels of oxLDL and regulate reactive oxygen species generation (ROS) in human monocyte derived macrophages (HMDMs). Compared to all compositions examined, nanoparticles with core ferulic acid-based polymers linked by diglycolic acid (PFAG) showed the greatest inhibition of oxLDL uptake. At high oxLDL concentrations, the ferulic acid diacids and polymer nanoparticles displayed similar oxLDL uptake. Treatment with the PFAG nanoparticles downregulated the expression of macrophage scavenger receptors, CD-36, MSR-1, and LOX-1 by about 20-50%, one of the causal factors for the decrease in oxLDL uptake. The PFAG nanoparticle lowered ROS production by HMDMs, which is important for maintaining macrophage growth and prevention of apoptosis. Based on these results, we propose that ferulic acid-based poly(anhydride ester) nanoparticles may offer an integrative strategy for the localized passivation of the early stages of the atheroinflammatory cascade in cardiovascular disease. Future development of anti-oxidant formulations for atherosclerosis applications is essential to deliver an efficacious dose while limiting localized concentrations of pro-oxidants. In this study, we illustrate the potential of degradable ferulic acid-based polymer nanoparticles to control macrophage foam cell formation by significantly reducing oxLDL uptake through downregulation of scavenger receptors, CD-36, MSR-1, and LOX-1. Another critical finding is the ability of the degradable ferulate-based polymer nanoparticles to lower macrophage reactive oxygen species (ROS) levels, a precursor to apoptosis and plaque escalation. The degradable ferulic acid-based polymer nanoparticles hold significant promise as a means to alter the treatment and progression of atherosclerosis. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Mifepristone enhances insulin-stimulated Akt phosphorylation and glucose uptake in skeletal muscle cells.

PubMed

Bernal-Sore, Izela; Navarro-Marquez, Mario; Osorio-Fuentealba, César; Díaz-Castro, Francisco; Del Campo, Andrea; Donoso-Barraza, Camila; Porras, Omar; Lavandero, Sergio; Troncoso, Rodrigo

2018-02-05

Mifepristone is the only FDA-approved drug for glycaemia control in patients with Cushing's syndrome and type 2 diabetes. Mifepristone also has beneficial effects in animal models of diabetes and patients with antipsychotic treatment-induced obesity. However, the mechanisms through which Mifepristone produces its beneficial effects are not completely elucidated. To determine the effects of mifepristone on insulin-stimulated glucose uptake on a model of L6 rat-derived skeletal muscle cells. Mifepristone enhanced insulin-dependent glucose uptake, GLUT4 translocation to the plasma membrane and Akt Ser 473 phosphorylation in L6 myotubes. In addition, mifepristone reduced oxygen consumption and ATP levels and increased AMPK Thr 172 phosphorylation. The knockdown of AMPK prevented the effects of mifepristone on insulin response. Mifepristone enhanced insulin-stimulated glucose uptake through a mechanism that involves a decrease in mitochondrial function and AMPK activation in skeletal muscle cells. Copyright © 2017 Elsevier B.V. All rights reserved.

The role of biological uptake in iron and manganese cycling in Lake Baikal

USGS Publications Warehouse

Granina, L.Z.; Callender, E.

2006-01-01

The role of biological uptake in the internal cycling of Fe and Mn in Lake Baikal was quantified. Biological uptake, sedimentation consisting of the biogenic and lithogenic fluxes, and remineralization have been evaluated. The results of calculations show that about 5-10% of Fe and Mn accumulated in the lake are annually taken up by biota. More than 80% of this amount is again recycled after remineralization of biological material. At this, the biogenic fluxes of Fe and Mn are 2-4 times less compared to lithogenic ones. Thus not only is oxidation of Fe and Mn within the water column highly enriched in the oxygen that results in settling of Fe and Mn oxides, but also intensive biological uptake of these elements contributes to their fast removal from internal cycling. However, essential remineralization makes this process of minor importance to Fe and Mn cycling in Lake Baikal. ?? Springer 2006.

Aeration costs in stirred-tank and bubble column bioreactors

DOE PAGES

Humbird, D.; Davis, R.; McMillan, J. D.

2017-08-10

To overcome knowledge gaps in the economics of large-scale aeration for production of commodity products, Aspen Plus is used to simulate steady-state oxygen delivery in both stirred-tank and bubble column bioreactors, using published engineering correlations for oxygen mass transfer as a function of aeration rate and power input, coupled with new equipment cost estimates developed in Aspen Capital Cost Estimator and validated against vendor quotations. Here, these simulations describe the cost efficiency of oxygen delivery as a function of oxygen uptake rate and vessel size, and show that capital and operating costs for oxygen delivery drop considerably moving from standard-sizemore » (200 m 3) to world-class size (500 m 3) reactors, but only marginally in further scaling up to hypothetically large (1000 m 3) reactors. Finally, this analysis suggests bubble-column reactor systems can reduce overall costs for oxygen delivery by 10-20% relative to stirred tanks at low to moderate oxygen transfer rates up to 150 mmol/L-h.« less

Aeration costs in stirred-tank and bubble column bioreactors

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

Humbird, D.; Davis, R.; McMillan, J. D.

To overcome knowledge gaps in the economics of large-scale aeration for production of commodity products, Aspen Plus is used to simulate steady-state oxygen delivery in both stirred-tank and bubble column bioreactors, using published engineering correlations for oxygen mass transfer as a function of aeration rate and power input, coupled with new equipment cost estimates developed in Aspen Capital Cost Estimator and validated against vendor quotations. Here, these simulations describe the cost efficiency of oxygen delivery as a function of oxygen uptake rate and vessel size, and show that capital and operating costs for oxygen delivery drop considerably moving from standard-sizemore » (200 m 3) to world-class size (500 m 3) reactors, but only marginally in further scaling up to hypothetically large (1000 m 3) reactors. Finally, this analysis suggests bubble-column reactor systems can reduce overall costs for oxygen delivery by 10-20% relative to stirred tanks at low to moderate oxygen transfer rates up to 150 mmol/L-h.« less

Enhancement of glucose uptake in skeletal muscle L6 cells and insulin secretion in pancreatic hamster-insulinoma-transfected cells by application of non-thermal plasma jet

NASA Astrophysics Data System (ADS)

Kumar, Naresh; Kaushik, Nagendra K.; Park, Gyungsoon; Choi, Eun H.; Uhm, Han S.

2013-11-01

Type-II diabetes Mellitus is characterized by defects in insulin action on peripheral tissues, such as skeletal muscle, adipose tissue, and liver and pancreatic beta cells. Since the skeletal muscle accounts for approximately 75% of insulin-stimulated glucose-uptake in our body, impaired insulin secretion from defected beta cell plays a major role in the afflicted glucose homoeostasis. It was shown that the intracellular reactive oxygen species and nitric oxide level was increased by non-thermal-plasma treatment in ambient air. These increased intracellular reactive species may enhance glucose uptake and insulin secretion through the activation of intracellular calcium (Ca+) and cAMP production.

Oxygen chemisorption and oxide formation on Ni silicide surfaces at room temperature

NASA Astrophysics Data System (ADS)

Valeri, S.; Del Pennino, U.; Lomellini, P.; Sassaroli, P.

1984-10-01

Auger spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) have been used in a comparative study of the room temperature oxidation of Ni silicides of increasing silicon content, from Ni3Si to NiSi2. The results were compared with those for the oxidation of pure Si and Ni. All suicide surfaces in the exposure range between 0.2 and 104 L follow two-step oxidation kinetics: the first step is characterized by an oxygen uptake rate higher than in the second one. Attention was focused on the oxygen induced modifications of metal and silicon AES and XPS spectra in silicides, which are indicative of changes in the local electronic structure and in the chemical bonding. In general oxygen bonds with silicon leaving the metal unaffected; however, at high exposures, characteristic feature of the Ni-oxygen bonds appear in the Ni(MVV) Auger line of the Ni-rich silicides. The presence of Ni atoms enhances considerably the Si oxidation process in silicides with respect to pure Si, in terms both of a higher Si oxidation state and a higher oxygen uptake; this enhancement is stronger in Ni-rich silicides than in Si-rich silicides. The oxygen induced contributions in the Si(LVV) Auger line show structures at 76 and 83 eV, and those in the Si 2p photoemission spectra show binding energy shifts between -1 and -3.8 eV; we conclude that the oxidation products are mainly silicon suboxides, like Si2O3 and SiO; only on Ni3 Si at 104 L, a significant contribution of SiO2 was found. The Ni catalytic effect on Si oxidation has been discussed in terms of the suicide heat of formation, of the breaking of the silicon sp3 configuration in silicides and of the metal atom dissociative effect on the O2 molecule.

The Moral Obligation to Explore the Military Use of Performance-Enhancing Supplements and Drugs

DTIC Science & Technology

2017-06-01

effects as well. Creatinine is a natural by-product of the consumption of creatine in the muscles during heavy exertion.131 Creatinine must then be...Basel: Karger Landes Systems, 1997), 9−18. 162 G. S. Hughes Jr. et al., “Hematologic Effects of a Novel Hemoglobin-Based Oxygen Carrier in Normal...like the regulation of blood pressure, neuroprotection, and maximum oxygen uptake.167 Moderate rHuEPO use has been shown to have beneficial effects

Cell uptake, intracellular distribution, fate and reactive oxygen species generation of polymer brush engineered CeO2-x NPs

NASA Astrophysics Data System (ADS)

Qiu, Yuan; Rojas, Elena; Murray, Richard A.; Irigoyen, Joseba; Gregurec, Danijela; Castro-Hartmann, Pablo; Fledderman, Jana; Estrela-Lopis, Irina; Donath, Edwin; Moya, Sergio E.

2015-04-01

Cerium Oxide nanoparticles (CeO2-x NPs) are modified with polymer brushes of negatively charged poly (3-sulfopropylmethacrylate) (PSPM) and positively charged poly (2-(methacryloyloxy)ethyl-trimethylammonium chloride) (PMETAC) by Atom Transfer Radical Polymerisation (ATRP). CeO2-x NPs are fluorescently labelled by covalently attaching Alexa Fluor® 488/Fluorescein isothiocyanate to the NP surface prior to polymerisation. Cell uptake, intracellular distribution and the impact on the generation of intracellular Reactive Oxygen Species (ROS) with respect to CeO2-x NPs are studied by means of Raman Confocal Microscopy (CRM), Transmission Electron Microscopy (TEM) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). PSPM and PMETAC coated CeO2-x NPs show slower and less uptake compared to uncoated Brush modified NPs display a higher degree of co-localisation with cell endosomes and lysosomes after 24 h of incubation. They also show higher co-localisation with lipid bodies when compared to unmodified CeO2-x NPs. The brush coating does not prevent CeO2-x NPs from displaying antioxidant properties.Cerium Oxide nanoparticles (CeO2-x NPs) are modified with polymer brushes of negatively charged poly (3-sulfopropylmethacrylate) (PSPM) and positively charged poly (2-(methacryloyloxy)ethyl-trimethylammonium chloride) (PMETAC) by Atom Transfer Radical Polymerisation (ATRP). CeO2-x NPs are fluorescently labelled by covalently attaching Alexa Fluor® 488/Fluorescein isothiocyanate to the NP surface prior to polymerisation. Cell uptake, intracellular distribution and the impact on the generation of intracellular Reactive Oxygen Species (ROS) with respect to CeO2-x NPs are studied by means of Raman Confocal Microscopy (CRM), Transmission Electron Microscopy (TEM) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). PSPM and PMETAC coated CeO2-x NPs show slower and less uptake compared to uncoated Brush modified NPs display a higher degree of co-localisation with cell endosomes and lysosomes after 24 h of incubation. They also show higher co-localisation with lipid bodies when compared to unmodified CeO2-x NPs. The brush coating does not prevent CeO2-x NPs from displaying antioxidant properties. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00884k

Effect of hemoglobin polymerization on oxygen transport in hemoglobin solutions.

PubMed

Budhiraja, Vikas; Hellums, J David

2002-09-01

The effect of hemoglobin (Hb) polymerization on facilitated transport of oxygen in a bovine hemoglobin-based oxygen carrier was studied using a diffusion cell. In high oxygen tension gradient experiments (HOTG) at 37 degrees C the diffusion of dissolved oxygen in polymerized Hb samples was similar to that in unpolymerized Hb solutions during oxygen uptake. However, in the oxygen release experiments, the transport by diffusion of dissolved oxygen was augmented by diffusion of oxyhemoglobin over a range of oxygen saturations. The augmentation was up to 30% in the case of polymerized Hb and up to 100% in the case of unpolymerized Hb solution. In experiments performed at constant, low oxygen tension gradients in the range of physiological significance, the augmentation effect was less than that in the HOTG experiments. Oxygen transport in polymerized Hb samples was approximately the same as that in unpolymerized samples over a wide range of oxygen tensions. However, at oxygen tensions lower than 30 mm Hg, there were more significant augmentation effects in unpolymerized bovine Hb samples than in polymerized Hb. The results presented here are the first accurate, quantitative measurements of effective diffusion coefficients for oxygen transport in hemoglobin-based oxygen carriers of the type being evaluated to replace red cells in transfusions. In all cases the oxygen carrier was found to have higher effective oxygen diffusion coefficients than blood.

Cationic Phosphorus Dendrimer Enhances Photodynamic Activity of Rose Bengal against Basal Cell Carcinoma Cell Lines.

PubMed

Dabrzalska, Monika; Janaszewska, Anna; Zablocka, Maria; Mignani, Serge; Majoral, Jean Pierre; Klajnert-Maculewicz, Barbara

2017-05-01

In the last couple of decades, photodynamic therapy emerged as a useful tool in the treatment of basal cell carcinoma. However, it still meets limitations due to unfavorable properties of photosensitizers such as poor solubility or lack of selectivity. Dendrimers, polymers widely studied in biomedical field, may play a role as photosensitizer carriers and improve the efficacy of photodynamic treatment. Here, we describe the evaluation of an electrostatic complex of cationic phosphorus dendrimer and rose bengal in such aspects as singlet oxygen production, cellular uptake, and phototoxicity against three basal cell carcinoma cell lines. Rose bengal-cationic dendrimer complex in molar ratio 5:1 was compared to free rose bengal. Obtained results showed that the singlet oxygen production in aqueous medium was significantly higher for the complex than for free rose bengal. The cellular uptake of the complex was 2-7-fold higher compared to a free photosensitizer. Importantly, rose bengal, rose bengal-dendrimer complex, and dendrimer itself showed no dark toxicity against all three cell lines. Moreover, we observed that phototoxicity of the complex was remarkably enhanced presumably due to high cellular uptake. On the basis of the obtained results, we conclude that rose bengal-cationic dendrimer complex has a potential in photodynamic treatment of basal cell carcinoma.

A study of water uptake by selected superdisintegrants from the sub-molecular to the particulate level.

PubMed

Barmpalexis, P; Syllignaki, P; Kachrimanis, K

2018-06-01

Water diffusion through the matrix of three superdisintegrants, namely sodium starch glycolate (SSG), croscarmellose sodium (cCMC-Na) and crospovidone (cPVP), was studied at the sub-molecular level using Attenuated Total Reflectance (ATR)-FTIR spectroscopy and molecular dynamics simulations, and the results were correlated to water uptake studies conducted at the particulate level using Parallel Exponential Kinetics (PEK) modeling in dynamic moisture sorption studies and optical microscopy. ATR-FTIR studies indicated that water diffuses inside cPVP by a single fast acting process, while in SSG and cCMC-Na, a slow and a fast process acting simultaneously, were identified. The same pattern regarding the rate of water uptake for all superdisintegrants was found also at the particulate level by PEK modeling. Moreover, molecular dynamics simulation helped elucidate the hydrogen bonding patterns formed between water-SSG and water-cCMC-Na, mainly via their carboxylic oxygen atoms and secondarily via their hydroxyl groups, while cPVP formed hydrogen bonds only through carbonyl oxygen. Finally, cPVP chains showed significant flexibility during hydration, while cCMC-Na and SSG chains retain their conformation to some extent, explaining the extensive swelling observed also at the particulate level by optical microscopy hydration studies.

Growth of Ammonium Bisulfate Clusters by Adsorption of Oxygenated Organic Molecules

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

DePalma, Joseph W.; Wang, Jian; Wexler, Anthony S.

Quantum chemical calculations were employed to model the interactions of the [(NH 4 +) 4(HSO 4 -) 4] ammonium bisulfate cluster with one or more molecular products of monoterpene oxidation. A strong interaction was found between the bisulfate ion of the cluster and a carboxylic acid, aldehyde or ketone functionality of the organic molecule. Free energies of adsorption for carboxylic acids were in the -70 to -73 kJ/mol range, while those for aldehydes and ketones were in the -46 to -50 kJ/mol range. These values suggest that a small ambient ammonium bisulfate cluster, such as the [(NH 4 +) 4(SOmore » 4 -) 4] cluster, is able to adsorb an oxygenated organic molecule. Although adsorption of the first molecule is highly favorable, adsorption of subsequent molecules is not, suggesting that sustained uptake of organic molecules does not occur, and thus is not a pathway for continuing growth of the cluster. This result is consistent with ambient measurements showing that particles below ~1 nm grow slowly, while those above 1 nm grow at an increasing rate presumably due to a lower surface energy barrier enabling the uptake of organic molecules. This work provides insight into the molecular level interactions which affect sustained cluster growth by uptake of organic molecules.« less

Growth of Ammonium Bisulfate Clusters by Adsorption of Oxygenated Organic Molecules

DOE PAGES

DePalma, Joseph W.; Wang, Jian; Wexler, Anthony S.; ...

2015-10-21

Quantum chemical calculations were employed to model the interactions of the [(NH 4 +) 4(HSO 4 -) 4] ammonium bisulfate cluster with one or more molecular products of monoterpene oxidation. A strong interaction was found between the bisulfate ion of the cluster and a carboxylic acid, aldehyde or ketone functionality of the organic molecule. Free energies of adsorption for carboxylic acids were in the -70 to -73 kJ/mol range, while those for aldehydes and ketones were in the -46 to -50 kJ/mol range. These values suggest that a small ambient ammonium bisulfate cluster, such as the [(NH 4 +) 4(SOmore » 4 -) 4] cluster, is able to adsorb an oxygenated organic molecule. Although adsorption of the first molecule is highly favorable, adsorption of subsequent molecules is not, suggesting that sustained uptake of organic molecules does not occur, and thus is not a pathway for continuing growth of the cluster. This result is consistent with ambient measurements showing that particles below ~1 nm grow slowly, while those above 1 nm grow at an increasing rate presumably due to a lower surface energy barrier enabling the uptake of organic molecules. This work provides insight into the molecular level interactions which affect sustained cluster growth by uptake of organic molecules.« less

Dissociation Between Brown Adipose Tissue 18F-FDG Uptake and Thermogenesis in Uncoupling Protein 1-Deficient Mice.

PubMed

Hankir, Mohammed K; Kranz, Mathias; Keipert, Susanne; Weiner, Juliane; Andreasen, Sille G; Kern, Matthias; Patt, Marianne; Klöting, Nora; Heiker, John T; Brust, Peter; Hesse, Swen; Jastroch, Martin; Fenske, Wiebke K

2017-07-01

18 F-FDG PET imaging is routinely used to investigate brown adipose tissue (BAT) thermogenesis, which requires mitochondrial uncoupling protein 1 (UCP1). It remains uncertain, however, whether BAT 18 F-FDG uptake is a reliable surrogate measure of UCP1-mediated heat production. Methods: UCP1 knockout (KO) and wild-type (WT) mice housed at thermoneutrality were treated with the selective β3 adrenergic receptor agonist CL 316, 243 and underwent metabolic cage, infrared thermal imaging and 18 F-FDG PET/MRI experiments. Primary brown adipocytes were additionally examined for their bioenergetics by extracellular flux analysis as well as their uptake of 2-deoxy- 3 H-glucose. Results: In response to CL 316, 243 treatments, oxygen consumption, and BAT thermogenesis were diminished in UCP1 KO mice, but BAT 18 F-FDG uptake was fully retained. Isolated UCP1 KO brown adipocytes exhibited defective induction of uncoupled respiration whereas their glycolytic flux and 2-deoxy- 3 H-glucose uptake rates were largely unaffected. Conclusion: Adrenergic stimulation can increase BAT 18 F-FDG uptake independently of UCP1 thermogenic function. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.

ESCA study of several fluorocarbon polymers exposed to atomic oxygen in low earth orbit or within or downstream from a radio-frequency oxygen plasma

NASA Technical Reports Server (NTRS)

Golub, Morton A.; Wydeven, Theodore; Cormia, Robert D.

1989-01-01

The ESCA (electron spectroscopy for chemical analysis) spectra of films of Tedlar, tetrafluoroethylene-hexafluoropropylene copolymer (in the form of a Teflon FEP coating on Kapton H, i.e., Kapton F), and polytetrafluoroethylene (Teflon or Teflon TFE), exposed to atomic oxygen O(3P) either in LEO on the STS-8 Space Shuttle or within or downstream from a radio-frequency oxygen plasma, were compared. The major difference in surface chemistry of Tedlar induced by the various exposures to O(3P) was a much larger uptake of oxygen when etched either in or out of the glow of an O2 plasma than when etched in LEO. In contrast, Kapton F exhibited very little surface oxidation during any of the three different exposures to O(3P), while Teflon was scarcely oxidized.

Children-Adult Comparisons of VO2 and HR Kinetics during Submaximum Exercise.

ERIC Educational Resources Information Center

Sady, Stanley P.; And Others

1983-01-01

Oxygen uptake and heart rate kinetics for submaximum exercise (bicycle riding) were compared in prepubescent boys and adult men. Resulting data suggest that children and adults do not differ significantly in cardiorespiratory adjustments during low-intensity exercise. (Authors/PP)

Effect of Exercise Training on Red Blood Cell Distribution Width as a Marker of Impaired Exercise Tolerance in Patients With Coronary Artery Disease.

PubMed

Nishiyama, Yasuhiro; Niiyama, Hiroshi; Harada, Haruhito; Katou, Atsushi; Yoshida, Noriko; Ikeda, Hisao

2016-09-28

Red blood cell distribution width (RDW) can predict mortality in cardiovascular disease. However, the underlying mechanisms of the beneficial prognostic marker remain unknown. The purpose of this study was to investigate whether the RDW is related to impaired exercise tolerance and exercise training (ET) effect on RDW in patients with coronary artery disease (CAD).Seventy-eight patients who underwent ET by supervised bicycle ergometer during 3 weeks served as the ET group whereas 30 patients who did not undergo ET were the control group. Exercise stress test with cardiopulmonary analysis was performed in the ET group. Peak oxygen uptake (from 14.1 ± 4.0 to 15.1 ± 3.8 mL/kg/minute, P < 0.05) significantly increased in the ET group. Although RDW and serum erythropoietin concentration (EP) before the observation period did not differ between the ET and control groups, RDW (from 44.4 ± 4.7 to 43.4 ± 3.8 fL, P < 0.01) and EP (from 27.9 ± 15.8 to 22.9 ± 8.2 mIU/mL, P < 0.005) significantly decreased in the ET group, however, these parameters did not change in the control group. In the ET group, RDW was negatively correlated with peak oxygen uptake (r = -0.55, P < 0.01) and the changes in RDW before and after ET were positively correlated with the changes in EP (r = 0.39, P < 0.005).Thus, ET increases exercise tolerance and decreases RDW in association with increased oxygen uptake in patients with CAD.

Estimation of Energy Expenditure during Treadmill Exercise via Thermal Imaging.

PubMed

Jensen, Martin Møller; Poulsen, Mathias Krogh; Alldieck, Thiemo; Larsen, Ryan Godsk; Gade, Rikke; Moeslund, Thomas Baltzer; Franch, Jesper

2016-12-01

Noninvasive imaging of oxygen uptake may provide a useful tool for the quantification of energy expenditure during human locomotion. A novel thermal imaging method (optical flow) was validated against indirect calorimetry for the estimation of energy expenditure during human walking and running. Fourteen endurance-trained subjects completed a discontinuous incremental exercise test on a treadmill. Subjects performed 4-min intervals at 3, 5, and 7 km·h (walking) and at 8, 10, 12, 14, 16, and 18 km·h (running) with 30 s of rest between intervals. Heart rate, gas exchange, and mean accelerations of ankle, thigh, wrist, and hip were measured throughout the exercise test. A thermal camera (30 frames per second) was used to quantify optical flow, calculated as the movements of the limbs relative to the trunk (internal mechanical work) and vertical movement of the trunk (external vertical mechanical work). Heart rate, gross oxygen uptake (mL·kg·min) together with gross and net energy expenditure (J·kg·min) rose with increasing treadmill velocities, as did optical flow measurements and mean accelerations (g) of ankle, thigh, wrist, and hip. Oxygen uptake was linearly correlated with optical flow across all exercise intensities (R = 0.96, P < 0.0001; V˙O2 [mL·kg·min] = 7.35 + 9.85 × optical flow [arbitrary units]). Only 3-4 s of camera recording was required to estimate an optical flow value at each velocity. Optical flow measurements provide an accurate estimation of energy expenditure during horizontal walking and running. The technique offers a novel experimental method of estimating energy expenditure during human locomotion, without use of interfering equipment attached to the subject.

Criterion-Related Validity of the Distance- and Time-Based Walk/Run Field Tests for Estimating Cardiorespiratory Fitness: A Systematic Review and Meta-Analysis.

PubMed

Mayorga-Vega, Daniel; Bocanegra-Parrilla, Raúl; Ornelas, Martha; Viciana, Jesús

2016-01-01

The main purpose of the present meta-analysis was to examine the criterion-related validity of the distance- and time-based walk/run tests for estimating cardiorespiratory fitness among apparently healthy children and adults. Relevant studies were searched from seven electronic bibliographic databases up to August 2015 and through other sources. The Hunter-Schmidt's psychometric meta-analysis approach was conducted to estimate the population criterion-related validity of the following walk/run tests: 5,000 m, 3 miles, 2 miles, 3,000 m, 1.5 miles, 1 mile, 1,000 m, ½ mile, 600 m, 600 yd, ¼ mile, 15 min, 12 min, 9 min, and 6 min. From the 123 included studies, a total of 200 correlation values were analyzed. The overall results showed that the criterion-related validity of the walk/run tests for estimating maximum oxygen uptake ranged from low to moderate (rp = 0.42-0.79), with the 1.5 mile (rp = 0.79, 0.73-0.85) and 12 min walk/run tests (rp = 0.78, 0.72-0.83) having the higher criterion-related validity for distance- and time-based field tests, respectively. The present meta-analysis also showed that sex, age and maximum oxygen uptake level do not seem to affect the criterion-related validity of the walk/run tests. When the evaluation of an individual's maximum oxygen uptake attained during a laboratory test is not feasible, the 1.5 mile and 12 min walk/run tests represent useful alternatives for estimating cardiorespiratory fitness. As in the assessment with any physical fitness field test, evaluators must be aware that the performance score of the walk/run field tests is simply an estimation and not a direct measure of cardiorespiratory fitness.

Routine and active metabolic rates of migrating adult wild sockeye salmon (Oncorhynchus nerka Walbaum) in seawater and freshwater.

PubMed

Wagner, G N; Kuchel, L J; Lotto, A; Patterson, D A; Shrimpton, J M; Hinch, S G; Farrell, A P

2006-01-01

We present the first data on the differences in routine and active metabolic rates for sexually maturing migratory adult sockeye salmon (Oncorhynchus nerka) that were intercepted in the ocean and then held in either seawater or freshwater. Routine and active oxygen uptake rates (MO2) were significantly higher (27%-72%) in seawater than in freshwater at all swimming speeds except those approaching critical swimming speed. During a 45-min recovery period, the declining postexercise oxygen uptake remained 58%-73% higher in seawater than in freshwater. When fish performed a second swim test, active metabolic rates again remained 28%-81% higher for fish in seawater except at the critical swimming speed. Despite their differences in metabolic rates, fish in both seawater and freshwater could repeat the swim test and reach a similar maximum oxygen uptake and critical swimming speed as in the first swim test, even without restoring routine metabolic rate between swim tests. Thus, elevated MO2 related to either being in seawater as opposed to freshwater or not being fully recovered from previous exhaustive exercise did not present itself as a metabolic loading that limited either critical swimming performance or maximum MO2. The basis for the difference in metabolic rates of migratory sockeye salmon held in seawater and freshwater is uncertain, but it could include differences in states of nutrition, reproduction, and restlessness, as well as ionic differences. Regardless, this study elucidates some of the metabolic costs involved during the migration of adult salmon from seawater to freshwater, which may have applications for fisheries conservation and management models of energy use.

Early diagenesis in the sediments of the Congo deep-sea fan dominated by massive terrigenous deposits: Part III - Sulfate- and methane- based microbial processes

NASA Astrophysics Data System (ADS)

Pastor, L.; Toffin, L.; Decker, C.; Olu, K.; Cathalot, C.; Lesongeur, F.; Caprais, J.-C.; Bessette, S.; Brandily, C.; Taillefert, M.; Rabouille, C.

2017-08-01

Geochemical profiles (SO42-, H2S, CH4, δ13CH4) and phylogenetic diversity of Archaea and Bacteria from two oceanographic cruises dedicated to the lobes sediments of the Congo deep-sea fan are presented in this paper. In this area, organic-rich turbidites reach 5000 m and allow the establishment of patchy cold-seep-like habitats including microbial mats, reduced sediments, and vesicomyid bivalves assemblages. These bivalves live in endosymbiosis with sulfur-oxidizing bacteria and use sulfides to perform chemosynthesis. In these habitats, unlike classical abyssal sediments, anoxic processes are dominant. Total oxygen uptake fluxes and methane fluxes measured with benthic chambers are in the same range as those of active cold-seep environments, and oxygen is mainly used for reoxidation of reduced compounds, especially in bacterial mats and reduced sediments. High concentrations of methane and sulfate co-exist in the upper 20 cm of sediments, and evidence indicates that sulfate-reducing microorganisms and methanogens co-occur in the shallow layers of these sediments. Simultaneously, anaerobic oxidation of methane (AOM) with sulfate as the electron acceptor is evidenced by the presence of ANMEs (ANaerobic MEthanotroph). Dissolved sulfide produced through the reduction of sulfate is reoxidized through several pathways depending on the habitat. These pathways include vesicomyid bivalves uptake (adults or juveniles in the bacterial mats habitats), reoxidation by oxygen or iron phases within the reduced sediment, or reoxidation by microbial mats. Sulfide uptake rates by vesicomyids measured in sulfide-rich sea water (90±18 mmol S m-2 d-1) were similar to sulfide production rates obtained by modelling the sulfate profile with different bioirrigation constants, highlighting the major control of vesicomyids on sulfur cycle in their habitats.

Determination of the exercise intensity that elicits maximal fat oxidation in individuals with obesity.

PubMed

Dandanell, Sune; Præst, Charlotte Boslev; Søndergård, Stine Dam; Skovborg, Camilla; Dela, Flemming; Larsen, Steen; Helge, Jørn Wulff

2017-04-01

Maximal fat oxidation (MFO) and the exercise intensity that elicits MFO (Fat Max ) are commonly determined by indirect calorimetry during graded exercise tests in both obese and normal-weight individuals. However, no protocol has been validated in individuals with obesity. Thus, the aims were to develop a graded exercise protocol for determination of Fat Max in individuals with obesity, and to test validity and inter-method reliability. Fat oxidation was assessed over a range of exercise intensities in 16 individuals (age: 28 (26-29) years; body mass index: 36 (35-38) kg·m -2 ; 95% confidence interval) on a cycle ergometer. The graded exercise protocol was validated against a short continuous exercise (SCE) protocol, in which Fat Max was determined from fat oxidation at rest and during 10 min of continuous exercise at 35%, 50%, and 65% of maximal oxygen uptake. Intraclass and Pearson correlation coefficients between the protocols were 0.75 and 0.72 and within-subject coefficient of variation (CV) was 5 (3-7)%. A Bland-Altman plot revealed a bias of -3% points of maximal oxygen uptake (limits of agreement: -12 to 7). A tendency towards a systematic difference (p = 0.06) was observed, where Fat Max occurred at 42 (40-44)% and 45 (43-47)% of maximal oxygen uptake with the graded and the SCE protocol, respectively. In conclusion, there was a high-excellent correlation and a low CV between the 2 protocols, suggesting that the graded exercise protocol has a high inter-method reliability. However, considerable intra-individual variation and a trend towards systematic difference between the protocols reveal that further optimization of the graded exercise protocol is needed to improve validity.

Prescribing 6-weeks of running training using parameters from a self-paced maximal oxygen uptake protocol.

PubMed

Hogg, James S; Hopker, James G; Coakley, Sarah L; Mauger, Alexis R

2018-05-01

The self-paced maximal oxygen uptake test (SPV) may offer effective training prescription metrics for athletes. This study aimed to examine whether SPV-derived data could be used for training prescription. Twenty-four recreationally active male and female runners were randomly assigned between two training groups: (1) Standardised (STND) and (2) Self-Paced (S-P). Participants completed 4 running sessions a week using a global positioning system-enabled (GPS) watch: 2 × interval sessions; 1 × recovery run; and 1 × tempo run. STND had training prescribed via graded exercise test (GXT) data, whereas S-P had training prescribed via SPV data. In STND, intervals were prescribed as 6 × 60% of the time that velocity at [Formula: see text] ([Formula: see text]) could be maintained (T max ). In S-P, intervals were prescribed as 7 × 120 s at the mean velocity of rating of perceived exertion 20 ( v RPE20). Both groups used 1:2 work:recovery ratio. Maximal oxygen uptake ([Formula: see text]), [Formula: see text], T max, v RPE20, critical speed (CS), and lactate threshold (LT) were determined before and after the 6-week training. STND and S-P training significantly improved [Formula: see text] by 4 ± 8 and 6 ± 6%, CS by 7 ± 7 and 3 ± 3%; LT by 5 ± 4% and 7 ± 8%, respectively (all P < .05), with no differences observed between groups. Novel metrics obtained from the SPV can offer similar training prescription and improvement in [Formula: see text], CS and LT compared to training derived from a traditional GXT.

Physiological effects of wearing graduated compression stockings during running.

PubMed

Ali, Ajmol; Creasy, Robert H; Edge, Johann A

2010-08-01

This study examined the effect of wearing different grades of graduated compression stockings (GCS) on physiological and perceptual measures during and following treadmill running in competitive runners. Nine males and one female performed three 40-min treadmill runs (80 +/- 5% maximal oxygen uptake) wearing either control (0 mmHg; CON), low (12-15 mmHg; LO-GCS), or high (23-32 mmHg; HI-GCS) grade GCS in a double-blind counterbalanced order. Oxygen uptake, heart rate and blood lactate were measured. Perceptual scales were used pre- and post-run to assess comfort, tightness and any pain associated with wearing GCS. Changes in muscle function, soreness and damage were determined pre-run, immediately after running and 24 and 48 h post-run by measuring creatine kinase and myoglobin, counter-movement jump height, perceived soreness diagrams, and pressure sensitivity. There were no significant differences between trials for oxygen uptake, heart rate or blood lactate during exercise. HI-GCS was perceived as tighter (P < 0.05) and more pain-inducing (P < 0.05) than the other interventions; CON and LO-GCS were rated more comfortable than HI-GCS (P < 0.05). Creatine kinase (P < 0.05), myoglobin (P < 0.05) and jump height (P < 0.05) were higher and pressure sensitivity was more pronounced (P < 0.05) immediately after running but not after 24 and 48 h. Only four participants reported muscle soreness during recovery from running and there were no differences in muscle function between trials. In conclusion, healthy runners wearing GCS did not experience any physiological benefits during or following treadmill running. However, athletes felt more comfortable wearing low-grade GCS whilst running.

Assessing the biodegradability of terrestrially-derived organic matter in Scottish sea loch sediments

NASA Astrophysics Data System (ADS)

Loh, P. S.; Miller, A. E. J.; Reeves, A. D.; Harvey, S. M.; Overnell, J.

2008-05-01

Lignin oxidation products, oxygen uptake rates, molar organic carbon to nitrogen (OC/N) ratio (from bulk elemental analysis) and Rp values (from loss on ignition experiments, the ratio of the refractory to total organic matter, OM) were determined for sediments along transects of Loch Creran and Loch Etive. Lignin data indicated the importance of riverine inputs contributing to land-derived carbon in the lochs as total lignin (Λ, mg/100 mg organic carbon, OC) decreased from 0.69 to 0.45 and 0.70 to 0.29 from the head to outside of Loch Creran and Loch Etive, respectively. In addition, significant correlations of lignin content against total OM and OC (p<0.05) also suggested a distinct contribution of terrestrial OM to carbon pools in the lochs. The general trend of decreasing oxygen uptake rates from the head (20.8 mmole m-2 day-1) to mouth (9.4 mmole m-2 day-1) of Loch Creran indicates decomposition of OM. Biodegradability of the sedimentary OM was also characterized by the increase of Rp values from the head to mouth of the lochs: 0.40 to 0.80 in Loch Etive and 0.43 to 0.63 in Loch Creran. Furthermore, the molar OC/N ratio decreased from 11.2 to 6.4 in Loch Creran, and from 17.5 to 8.2 in Loch Etive. Derived rate constants for OM degradation were found to decrease from LC0 to LC1, and increase from RE5 to RE6. This work demonstrates that oxygen uptake rates, Rp values and molar OC/N ratio are able to serve as useful proxies to indicate the biodegradability of sedimentary OM.

Effect of high-intensity training versus moderate training on peak oxygen uptake and chronotropic response in heart transplant recipients: a randomized crossover trial.

PubMed

Dall, C H; Snoer, M; Christensen, S; Monk-Hansen, T; Frederiksen, M; Gustafsson, F; Langberg, H; Prescott, E

2014-10-01

In heart transplant (HTx) recipients, there has been reluctance to recommend high-intensity interval training (HIIT) due to denervation and chronotropic impairment of the heart. We compared the effects of 12 weeks' HIIT versus continued moderate exercise (CON) on exercise capacity and chronotropic response in stable HTx recipients >12 months after transplantation in a randomized crossover trial. The study was completed by 16 HTx recipients (mean age 52 years, 75% males). Baseline peak oxygen uptake (VO2peak ) was 22.9 mL/kg/min. HIIT increased VO2peak by 4.9 ± 2.7 mL/min/kg (17%) and CON by 2.6 ± 2.2 mL/kg/min (10%) (significantly higher in HIIT; p < 0.001). During HIIT, systolic blood pressure decreased significantly (p = 0.037) with no significant change in CON (p = 0.241; between group difference p = 0.027). Peak heart rate (HRpeak ) increased significantly by 4.3 beats per minute (p = 0.014) after HIIT with no significant change in CON (p = 0.34; between group difference p = 0.027). Heart rate recovery (HRrecovery ) improved in both groups with a trend toward greater improvement after HIIT. The 5-month washout showed a significant loss of improvement. HIIT was well tolerated, had a superior effect on oxygen uptake, and led to an unexpected increase in HRpeak accompanied by a faster HRrecovery . This indicates that the benefits of HIIT are partly a result of improved chronotropic response. © Copyright 2014 The American Society of Transplantation and the American Society of Transplant Surgeons.

Peak oxygen uptake and left ventricular ejection fraction, but not depressive symptoms, are associated with cognitive impairment in patients with chronic heart failure

PubMed Central

Steinberg, Gerrit; Lossnitzer, Nicole; Schellberg, Dieter; Mueller-Tasch, Thomas; Krueger, Carsten; Haass, Markus; Ladwig, Karl Heinz; Herzog, Wolfgang; Juenger, Jana

2011-01-01

Background The aim of the present study was to assess cognitive impairment in patients with chronic heart failure (CHF) and its associations with depressive symptoms and somatic indicators of illness severity, which is a matter of controversy. Methods and results Fifty-five patients with CHF (mean age 55.3 ± 7.8 years; 80% male; New York Heart Association functional class I–III) underwent assessment with an expanded neuropsychological test battery (eg, memory, complex attention, mental flexibility, psychomotor speed) to evaluate objective and subjective cognitive impairment. Depressive symptoms were assessed using the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (SCID) and a self-report inventory (Hospital Anxiety and Depression Scale [HADS]). A comprehensive clinical dataset, including left ventricular ejection fraction, peak oxygen uptake, and a 6-minute walk test, was obtained for all patients. Neuropsychological functioning revealed impairment in 56% of patients in at least one measure of our neuropsychological test battery. However, the Mini Mental State Examination (MMSE) could only detect cognitive impairment in 1.8% of all patients, 24% had HADS scores indicating depressive symptoms, and 11.1% met SCID criteria for a depressive disorder. No significant association was found between depressive symptoms and cognitive impairment. Left ventricular ejection fraction was related to subjective cognitive impairment, and peak oxygen uptake was related to objective cognitive impairment. Conclusion Cognitive functioning was substantially reduced in patients with CHF and should therefore be diagnosed and treated in routine clinical practice. Caution is advised when the MMSE is used to identify cognitive impairment in patients with CHF. PMID:22267941

Deceptive meaning of oxygen uptake measured at the anaerobic threshold in patients with systolic heart failure and atrial fibrillation.

PubMed

Magrì, Damiano; Agostoni, Piergiuseppe; Corrà, Ugo; Passino, Claudio; Scrutinio, Domenico; Perrone-Filardi, Pasquale; Correale, Michele; Cattadori, Gaia; Metra, Marco; Girola, Davide; Piepoli, Massimo F; Iorio, AnnaMaria; Emdin, Michele; Raimondo, Rosa; Re, Federica; Cicoira, Mariantonietta; Belardinelli, Romualdo; Guazzi, Marco; Limongelli, Giuseppe; Clemenza, Francesco; Parati, Gianfranco; Frigerio, Maria; Casenghi, Matteo; Scardovi, Angela B; Ferraironi, Alessandro; Di Lenarda, Andrea; Bussotti, Maurizio; Apostolo, Anna; Paolillo, Stefania; La Gioia, Rocco; Gargiulo, Paola; Palermo, Pietro; Minà, Chiara; Farina, Stefania; Battaia, Elisa; Maruotti, Antonello; Pacileo, Giuseppe; Contini, Mauro; Oliva, Fabrizio; Ricci, Roberto; Sinagra, Gianfranco

2015-08-01

Oxygen uptake at the anaerobic threshold (VO2AT), a submaximal exercise-derived variable, independent of patients' motivation, is a marker of outcome in heart failure (HF). However, previous evidence of VO2AT values paradoxically higher in HF patients with permanent atrial fibrillation (AF) than in those with sinus rhythm (SR) raised uncertainties. We tested the prognostic role of VO2AT in a large cohort of systolic HF patients, focusing on possible differences between SR and AF. Altogether 2976 HF patients (2578 with SR and 398 with AF) were prospectively followed. Besides a clinical examination, each patient underwent a maximal cardiopulmonary exercise test (CPET). The follow-up was analysed for up to 1500 days. Cardiovascular death or urgent cardiac transplantation occurred in 303 patients (250 (9.6%) patients with SR and 53 (13.3%) patients with AF, p = 0.023). In the entire population, multivariate analysis including peak oxygen uptake (VO2) showed a prognostic capacity (C-index) similar to that obtained including VO2AT (0.76 vs 0.72). Also, left ventricular ejection fraction, ventilation vs carbon dioxide production slope, β-blocker and digoxin therapy proved to be significant prognostic indexes. The receiver-operating characteristic (ROC) curves analysis showed that the best predictive VO2AT cut-off for the SR group was 11.7 ml/kg/min, while it was 12.8 ml/kg/min for the AF group. VO2AT, a submaximal CPET-derived parameter, is reliable for long-term cardiovascular mortality prognostication in stable systolic HF. However, different VO2AT cut-off values between SR and AF HF patients should be adopted. © The European Society of Cardiology 2014.

Effect of +Gz Acceleration on the Oxygen Uptake-Excercise Load Relationship during Lower Extremity Ergometer Excercise

NASA Technical Reports Server (NTRS)

Jackson, Catherine G. R.

1996-01-01

Long term spaceflight and habitation of a space station and/or the moon require that astronauts be provided with sufficient environmental and physiological support so that they can not only function in microgravity but be returned to earth safely. As the duration of habitation in microgravity increase the effects of the concomitant deconditioning of body systems becomes a concern for added exercise in space and for reentry to Earth gravity. Many countermeasures have been proposed to maintain proper functioning of the body, but none have proved sufficient, especially when the cost of crew time spent in these activities is considered. The issue of appropriate countermeasures remains unresolved. Spaceflight deconditioning decreases tolerance to +Gz acceleration, head to foot, the direction which is experienced during reentry; the result is that the crew member is more prone to becoming pre-syncopal or syncopal, thus exacerbating the orthostatic intolerance. All ground-based research using microgravity analogues has produced this same lowered G tolerance. When intermittent exposure to +1 to +4 Gz acceleration training was used, some alleviation of orthosatic intolerance and negative physiological effects of deconditioning occurred. Exercise alone was not as effective; but the added G force was. The physiological responses to acceleration added to exercise training have not been clearly shown. We will test the hypothesis that there will be no difference in the exercise oxygen uptake-exercise load relationship with added +Gz acceleration. We wi also compare oxygen uptake during graded exercise-acceleration loads in the human-powered short arm centrifuge with those from normal supine exercise loads. The human-powered short arm centrifuge was built by NASA engineers at Ames Research Center.

Dietary acid load and renal function have varying effects on blood acid-base status and exercise performance across age and sex.

PubMed

Hietavala, Enni-Maria; Stout, Jeffrey R; Frassetto, Lynda A; Puurtinen, Risto; Pitkänen, Hannu; Selänne, Harri; Suominen, Harri; Mero, Antti A

2017-12-01

Diet composition influences acid-base status of the body. This may become more relevant as renal functional capacity declines with aging. We examined the effects of low (LD) versus high dietary acid load (HD) on blood acid-base status and exercise performance. Participants included 22 adolescents, 33 young adults (YA), and 33 elderly (EL), who followed a 7-day LD and HD in a randomized order. At the end of both diet periods the subjects performed a cycle ergometer test (3 × 10 min at 35%, 55%, 75%, and (except EL) until exhaustion at 100% of maximal oxygen uptake). At the beginning of and after the diet periods, blood samples were collected at rest and after all workloads. Oxygen uptake, respiratory exchange ratio (RER), and heart rate (HR) were monitored during cycling. In YA and EL, bicarbonate (HCO 3 - ) and base excess (BE) decreased over the HD period, and HCO 3 - , BE, and pH were lower at rest after HD compared with LD. In YA and EL women, HCO 3 - and BE were lower at submaximal workloads after HD compared with LD. In YA women, the maximal workload was 19% shorter and maximal oxygen uptake, RER, and HR were lower after HD compared with LD. Our data uniquely suggests that better renal function is associated with higher availability of bases, which may diminish exercise-induced acidosis and improve maximal aerobic performance. Differences in glomerular filtration rate between the subject groups likely explains the larger effects of dietary acid load in the elderly compared with younger subjects and in women compared with men.

Monitoring wheat mitochondrial compositional and respiratory changes using Fourier transform mid-infrared spectroscopy in response to agrochemical treatments

NASA Astrophysics Data System (ADS)

Pedersen, Matthew; Wegner, Casey; Phansak, Piyaporn; Sarath, Gautam; Gaussoin, Roch; Schlegel, Vicki

2017-02-01

Fungicides and plant growth regulators can impact plant growth outside of their effects on fungal pathogens. Although many of these chemicals are inhibitors of mitochondrial oxygen uptake, information remains limited as to whether they are able to modify other mitochondrial constituents. Fourier transform mid-infrared spectroscopy (FT-mIR) offers a high sample throughput method to comparatively and qualitatively evaluate the effects of exogenously added compounds on mitochondrial components. Therefore the objective of this study was to determine the ability of FT-mIR to detect effects mitochondrial fractions isolated from wheat (Triticum aestivum L.) seedlings in response to several agrochemical treatments, with an emphasis on fungicides. The accessed need was to develop FT-mIR analytical and statistical routines as an effective approach to differentiate spectra obtained from chemically-treated or untreated mitochondria. An NADH-dependent oxygen uptake approach was initially used as a comparative method to determine whether the fungicides (azoxystrobin, boscalid, cyazofamid, fluazinam, isopyrazam, and pyraclostrobin) and the plant growth regulator, (trinexapac-ethyl) reduced respiration inhibition on isolated mitochondria. Pyraclostrobin was the most effective inhibitor, whereas amisulbrom did not impact oxygen uptake. However, hierarchical clustering of FT-mIR spectra of isolated mitochondria treated with these different compounds separated into clades consistent with each of their expected mode of action. Analysis of the FT-mIR amide protein region indicated that amisulbrom and pyraclostrobin interacted with the isolated wheat mitochondria. Both chemicals were statistically different from the control signifying that respiration was indeed influenced by these treatments. Moreover, the entire FT-mIR region showed differences in various biological bands thereby providing additional information on mitochondria responses to agrochemicals, if so warranted.

Exercise for Preventing Hospitalization and Readmission in Adults with Congestive Heart Failure.

PubMed

Aronow, Wilbert S; Shamliyan, Tatyana A

2018-05-04

We critically appraised all available evidence regarding exercise interventions for improving patient survival and reducing hospital admissions in adults with chronic heart failure (HF). We searched 4 databases up to April 2018 and graded the quality of evidence according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group approach. We reviewed 7 meta-analyses and the publications of 48 randomized, controlled trials (RCT). In HF with reduced ejection fraction, low-quality evidence suggests that exercise prevents all-cause hospitalizations (RR 0.77; 95% CI 0.63;0.93; 1328 patients in 15 RCTs) and hospitalizations due to HF (RR 0.57; 95% CI 0.37;0.88; 1073 patients in 13 RCTs) and improves quality of life (standardized mean difference [SMD] -0.37; 95% CI -0.60;-0.14; 1270 patients in 25 RCTs) but has no effect on mortality. In HF with preserved ejection fraction, low-quality evidence suggests that exercise improves peak oxygen uptake (mean difference [MD] 2.36; 95% CI 1.16;3.57; 171 patients in 3 RCTs) and quality of life (MD -4.65; 95% CI -8.46;-0.83; 203 patients in 4 RCTs). In patients after heart transplantation, low-quality evidence suggests that exercise improves peak oxygen uptake (SMD 0.68; 95% CI 0.43;0.93; 284 patients in 9 RCTs) but does not improve quality of life. In order to reduce hospitalization and improve quality of life for adults with HF and reduced ejection fraction, clinicians should recommend exercise interventions. For adults with HF and preserved ejection fraction and in those undergoing heart transplantation, clinicians may recommend exercise interventions in order to improve peak oxygen uptake.

New Generalized Equation for Predicting Maximal Oxygen Uptake (from the Fitness Registry and the Importance of Exercise National Database).

PubMed

Kokkinos, Peter; Kaminsky, Leonard A; Arena, Ross; Zhang, Jiajia; Myers, Jonathan

2017-08-15

Impaired cardiorespiratory fitness (CRF) is closely linked to chronic illness and associated with adverse events. The American College of Sports Medicine (ACSM) regression equations (ACSM equations) developed to estimate oxygen uptake have known limitations leading to well-documented overestimation of CRF, especially at higher work rates. Thus, there is a need to explore alternative equations to more accurately predict CRF. We assessed maximal oxygen uptake (VO 2 max) obtained directly by open-circuit spirometry in 7,983 apparently healthy subjects who participated in the Fitness Registry and the Importance of Exercise National Database (FRIEND). We randomly sampled 70% of the participants from each of the following age categories: <40, 40 to 50, 50 to 70, and ≥70 and used the remaining 30% for validation. Multivariable linear regression analysis was applied to identify the most relevant variables and construct the best prediction model for VO 2 max. Treadmill speed and treadmill speed × grade were considered in the final model as predictors of measured VO 2 max and the following equation was generated: VO 2 max in ml O 2 /kg/min = speed (m/min) × (0.17 + fractional grade × 0.79) + 3.5. The FRIEND equation predicted VO 2 max with an overall error >4 times lower than the error associated with the traditional ACSM equations (5.1 ± 18.3% vs 21.4 ± 24.9%, respectively). Overestimation associated with the ACSM equation was accentuated when different protocols were considered separately. In conclusion, The FRIEND equation predicts VO 2 max more precisely than the traditional ACSM equations with an overall error >4 times lower than that associated with the ACSM equations. Published by Elsevier Inc.

Functional structure of laminated microbial sediments from a supratidal sandy beach of the German Wadden Sea (St. Peter-Ording)

NASA Astrophysics Data System (ADS)

Bühring, Solveig I.; Kamp, Anja; Wörmer, Lars; Ho, Stephanie; Hinrichs, Kai-Uwe

2014-01-01

Hidden for the untrained eye through a thin layer of sand, laminated microbial sediments occur in supratidal beaches along the North Sea coast. The inhabiting microbial communities organize themselves in response to vertical gradients of light, oxygen or sulfur compounds. We performed a fine-scale investigation on the vertical zonation of the microbial communities using a lipid biomarker approach, and assessed the biogeochemical processes using a combination of microsensor measurements and a 13C-labeling experiment. Lipid biomarker fingerprinting showed the overarching importance of cyanobacteria and diatoms in these systems, and heterocyst glycolipids revealed the presence of diazotrophic cyanobacteria even in 9 to 20 mm depth. High abundance of ornithine lipids (OL) throughout the system may derive from sulfate reducing bacteria, while a characteristic OL profile between 5 and 8 mm may indicate presence of purple non-sulfur bacteria. The fate of 13C-labeled bicarbonate was followed by experimentally investigating the uptake into microbial lipids, revealing an overarching importance of cyanobacteria for carbon fixation. However, in deeper layers, uptake into purple sulfur bacteria was evident, and a close microbial coupling could be shown by uptake of label into lipids of sulfate reducing bacteria in the deepest layer. Microsensor measurements in sediment cores collected at a later time point revealed the same general pattern as the biomarker analysis and the labeling experiments. Oxygen and pH-microsensor profiles showed active photosynthesis in the top layer. The sulfide that diffuses from deeper down and decreases just below the layer of active oxygenic photosynthesis indicates the presence of sulfur bacteria, like anoxygenic phototrophs that use sulfide instead of water for photosynthesis.

Biochar soil amendment on alleviation of drought and salt stress in plants: a critical review.

PubMed

Ali, Shafaqat; Rizwan, Muhammad; Qayyum, Muhammad Farooq; Ok, Yong Sik; Ibrahim, Muhammad; Riaz, Muhammad; Arif, Muhammad Saleem; Hafeez, Farhan; Al-Wabel, Mohammad I; Shahzad, Ahmad Naeem

2017-05-01

Drought and salt stress negatively affect soil fertility and plant growth. Application of biochar, carbon-rich material developed from combustion of biomass under no or limited oxygen supply, ameliorates the negative effects of drought and salt stress on plants. The biochar application increased the plant growth, biomass, and yield under either drought and/or salt stress and also increased photosynthesis, nutrient uptake, and modified gas exchange characteristics in drought and salt-stressed plants. Under drought stress, biochar increased the water holding capacity of soil and improved the physical and biological properties of soils. Under salt stress, biochar decreased Na + uptake, while increased K + uptake by plants. Biochar-mediated increase in salt tolerance of plants is primarily associated with improvement in soil properties, thus increasing plant water status, reduction of Na + uptake, increasing uptake of minerals, and regulation of stomatal conductance and phytohormones. This review highlights both the potential of biochar in alleviating drought and salt stress in plants and future prospect of the role of biochar under drought and salt stress in plants.

Facilitation of trace metal uptake in cells by inulin coating of metallic nanoparticles

NASA Astrophysics Data System (ADS)

Santillán-Urquiza, Esmeralda; Arteaga-Cardona, Fernando; Torres-Duarte, Cristina; Cole, Bryan; Wu, Bing; Méndez-Rojas, Miguel A.; Cherr, Gary N.

2017-09-01

Trace elements such as zinc and iron are essential for the proper function of biochemical processes, and their uptake and bioavailability are dependent on their chemical form. Supplementation of trace metals through nanostructured materials is a new field, but its application raises concerns regarding their toxicity. Here, we compared the intracellular zinc uptake of different sources of zinc: zinc sulfate, and ZnO and core-shell α-Fe2O3@ZnO nanoparticles, coated or uncoated with inulin, an edible and biocompatible polysaccharide. Using mussel haemocytes, a well-known model system to assess nanomaterial toxicity, we simultaneously assessed zinc accumulation and multiple cellular response endpoints. We found that intracellular zinc uptake was strongly enhanced by inulin coating, in comparison to the uncoated nanoparticles, while no significant effects on cell death, cell viability, mitochondrial membrane integrity, production of reactive oxygen species or lysosome abundance were observed at concentrations up to 20 ppm. Since no significant increments in toxicity were observed, the coated nanomaterials may be useful to increase in vivo zinc uptake for nutritional applications.

An oil-based model of inhalation anesthetic uptake and elimination.

PubMed

Loughlin, P J; Bowes, W A; Westenskow, D R

1989-08-01

An oil-based model was developed as a physical simulation of inhalation anesthetic uptake and elimination. It provides an alternative to animal models in testing the performance of anesthesia equipment. A 7.5-1 water-filled manometer simulates pulmonary mechanics. Nitrogen and carbon dioxide flowing into the manometer simulate oxygen consumption and carbon dioxide production. Oil-filled chambers (180 ml and 900 ml) simulate the uptake and washout of halothane by the vessel-rich and muscle tissue groups. A 17.2-1 air-filled chamber simulates uptake by the lung group. Gas circulates through the chambers (3.7, 13.8, and 25 l/min) to simulate the transport of anesthetic to the tissues by the circulatory system. Results show that during induction and washout, the rate of rise in endtidal halothane fraction simulated by the model parallels that measured in patients. The model's end-tidal fraction changes correctly with changes in cardiac output and alveolar ventilation. The model has been used to test anesthetic controllers and to evaluate gas sensors, and should be useful in teaching principles underlying volatile anesthetic uptake.

Tensile properties of V-Cr-Ti alloys after exposure in helium and low-partial-pressure oxygen environments

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

Natesan, K.; Soppet, W.K.

1997-04-01

A test program is in progress to evaluate the effect of oxygen at low pO{sub 2} on the tensile properties of V-(4-5)wt% Cr-(4-5)wt% Ti alloys. Some of the tensile specimens were precharged with oxygen at low pO{sub 2} at 500{degrees}C and reannealed in vacuum at 500{degrees}C in environments with various pO{sub 2} levels and subsequently tensile tested at room temperature. The preliminary results indicate that both approaches are appropriate for evaluating the effect of oxygen uptake on the tensile properties of the alloys. The data showed that in the relatively short-time tests conducted thus far, the maximum engineering stress slightlymore » increased after oxygen exposure but the uniform and total elongation values exhibited significant decrease after exposure in oxygen-containing environments. The data for a specimen exposed to a helium environment were similar to those obtained in low pO{sub 2} environments.« less

Computer-aided discovery of a metal-organic framework with superior oxygen uptake.

PubMed

Moghadam, Peyman Z; Islamoglu, Timur; Goswami, Subhadip; Exley, Jason; Fantham, Marcus; Kaminski, Clemens F; Snurr, Randall Q; Farha, Omar K; Fairen-Jimenez, David

2018-04-11

Current advances in materials science have resulted in the rapid emergence of thousands of functional adsorbent materials in recent years. This clearly creates multiple opportunities for their potential application, but it also creates the following challenge: how does one identify the most promising structures, among the thousands of possibilities, for a particular application? Here, we present a case of computer-aided material discovery, in which we complete the full cycle from computational screening of metal-organic framework materials for oxygen storage, to identification, synthesis and measurement of oxygen adsorption in the top-ranked structure. We introduce an interactive visualization concept to analyze over 1000 unique structure-property plots in five dimensions and delimit the relationships between structural properties and oxygen adsorption performance at different pressures for 2932 already-synthesized structures. We also report a world-record holding material for oxygen storage, UMCM-152, which delivers 22.5% more oxygen than the best known material to date, to the best of our knowledge.

Comparison of the oxygen exchange between photosynthetic cell suspensions and detached leaves of Euphorbia characias L

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

Carrier, P.; Chagvardieff, P.; Tapie, P.

1989-11-01

Using a mass-spectrometric {sup 16}O{sub 2}/{sup 18}O{sub 2}-isotope technique, we compared the nature and the relative importance of oxygen exchange in photomixotrophic (PM) and photoautotrophic (PA) suspensions of Euphorbia characias L. with those in intact leaves of the same species. Young and mature leaves, dividing and nondividing cell suspensions were characterized in short-term experiments. On chlorophyll basis, the gross photosynthetic activities at CO{sub 2} saturating concentration of PA and PM suspensions varied little from those of leaves. On dry weight basis, gross photosynthesis of PA suspensions was equal to that of leaves because of their similar chlorophyll content. This wasmore » not the case in PM suspensions where gross photosynthesis was lower and largely varied during the growth cycle. The CO{sub 2} compensation point of PA cells was much higher than that of leaves. Oxygen uptakes were analyzed in terms of mitochondrial respiration, photorespiration and light stimulation of oxygen uptake (LSOU), often identified to Mehler-type reactions. In Pa and PM suspensions, mitochondrial respiration rates were higher than in leaves by a factor of 1.5 to 4.5. In PM suspensions, photorespiration and LSOU were observed only in nondividing cells. Photorespiration and LSOU rates were comparable in PA suspensions and leaves. Our results demonstrate that photorespiration of PA suspensions has not been affected by the 2% CO{sub 2} concentration imposed during 2 years of culture.« less

Characterization of Cardiopulmonary Exercise Testing Variables in Patients with Endomyocardial Fibrosis after Endocardial Resection

PubMed Central

Sayegh, Ana Luiza C.; dos Santos, Marcelo R.; de Oliveira, Patricia; Fernandes, Fábio; Rondon, Eduardo; de Souza, Francis R.; Salemi, Vera M. C.; Alves, Maria Janieire de N. N.; Mady, Charles

2017-01-01

Background Endomyocardial fibrosis (EMF) is a rare disease, characterized by diastolic dysfunction which leads to reduced peak oxygen consumption (VO2). Cardiopulmonary exercise testing (CPET) has been proved to be a fundamental tool to identify central and peripheral alterations. However, most studies prioritize peak VO2 as the main variable, leaving aside other important CPET variables that can specify the severity of the disease and guide the clinical treatment. Objective The aim of this study was to evaluate central and peripheral limitations in symptomatic patients with EMF by different CPET variables. Methods Twenty-six EMF patients (functional class III, NYHA) were compared with 15 healthy subjects (HS). Functional capacity was evaluated using CPET and diastolic and systolic functions were evaluated by echocardiography. Results Age and gender were similar between EMF patients and HS. Left ventricular ejection fraction was normal in EMF patients, but decreased compared to HS. Peak heart rate, peak workload, peak VO2, peak oxygen (O2) pulse and peak pulmonary ventilation (VE) were decreased in EMF compared to HS. Also, EMF patients showed increased Δ heart rate /Δ oxygen uptake and Δ oxygen uptake /Δ work rate compared to HS. Conclusion Determination of the aerobic capacity by noninvasive respiratory gas exchange during incremental exercise provides additional information about the exercise tolerance in patients with EMF. The analysis of different CPET variables is necessary to help us understand more about the central and peripheral alterations cause by both diastolic dysfunction and restrictive pattern. PMID:29364349

Influence of substrate surface loading on the kinetic behaviour of aerobic granules.

PubMed

Liu, Yu; Liu, Yong-Qiang; Wang, Zhi-Wu; Yang, Shu-Fang; Tay, Joo-Hwa

2005-06-01

In the aerobic granular sludge reactor, the substrate loading is related to the size of the aerobic granules cultivated. This study investigated the influence of substrate surface loading on the growth and substrate-utilization kinetics of aerobic granules. Results showed that microbial surface growth rate and surface biodegradation rate are fairly related to the substrate surface loading by the Monod-type equation. In this study, both the theoretical maximum growth yield and the Pirt maintenance coefficient were determined. It was found that the estimated theoretical maximum growth yield of aerobic granules was as low as 0.2 g biomass g(-1) chemical oxygen demand (COD) and 10-40% of input substrate-COD was consumed through the maintenance metabolism, while experimental results further showed that the unit oxygen uptake by aerobic granules was 0.68 g oxygen g(-1) COD, which was much higher than that reported in activated sludge processes. Based on the growth yield and unit oxygen uptake determined, an oxidative assimilation equation of acetate-fed aerobic granules was derived; and this was confirmed by respirometric tests. In aerobic granular culture, about 74% of the input substrate-carbon was converted to carbon dioxide. The growth yield of aerobic granules was three times lower than that of activated sludge. It is likely that high carbon dioxide production is the main cause of the low growth yield of aerobic granules, indicating a possible energy uncoupling in aerobic granular culture.

Oxygen uptake efficiency slope and peak oxygen consumption predict prognosis in children with tetralogy of Fallot.

PubMed

Tsai, Yun-Jeng; Li, Min-Hui; Tsai, Wan-Jung; Tuan, Sheng-Hui; Liao, Tin-Yun; Lin, Ko-Long

2016-07-01

Oxygen uptake efficiency slope (OUES) and peak oxygen consumption (VO2peak) are exercise parameters that can predict cardiac morbidity in patients with numerous heart diseases. But the predictive value in patients with tetralogy of Fallot is still undetermined, especially in children. We evaluated the prognostic value of OUES and VO2peak in children with total repair of tetralogy of Fallot. Retrospective cohort study. Forty tetralogy of Fallot patients younger than 12 years old were recruited. They underwent a cardiopulmonary exercise test during the follow-up period after total repair surgery. The results of the cardiopulmonary exercise test were used to predict the cardiac related hospitalization in the following two years after the test. OUES normalized by body surface area (OUES/BSA) and the percentage of predicted VO2peak appeared to be predictive for two-year cardiac related hospitalization. Receiver operating characteristic curve analysis demonstrated that the best threshold value for OUES/BSA was 1.029 (area under the curve = 0.70, p = 0.03), and for VO2peak was 74% of age prediction (area under the curve = 0.72, p = 0.02). The aforementioned findings were confirmed by Kaplan-Meier plots and log-rank test. OUES/BSA and VO2peak are useful predictors of cardiac-related hospitalization in children with total repair of tetralogy of Fallot. © The European Society of Cardiology 2015.

Survey of selected seaweeds for simultaneous photoproduction of hydrogen and oxygen

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

Greenbaum, E.; Ramus, J.

1983-03-01

Then seaweed species were surveyed for simultaneous photoevolution of hydrogen and oxygen. In an attempt to induce hydrogenase activity (as measured by hydrogen photoproduction) the seaweeds were maintained under anaerobiosis in CO/sub 2/-free seawater for varying lengths of time. Although oxygen evolution was observed in every alga studied, hydrogen evolution was not observed. One conclusion of this research is that, in contrast to the microscopic algae, there is not a single example of a macroscopic alga for which the photoevolution of hydrogen has been observed, in spite of the fact that there are now at least nine macroscopic algal speciesmore » known for which hydrogenase activity has been reported (either by dark hydrogen evolution or light-activated hydrogen uptake). These results are in conflict with the conventional view that algal hydrogenase can catalyze a multiplicity of reactions, one of which is the photoproduction of molecular hydrogen. Two possible explanations for the lack of hydrogen photoproduction in macroscopic algae are presented. It is postulated that electron acceptors other than carbon dioxide can take up reducing equivalents from Photosystem I to the measurable exclusion of hydrogen photoproduction. Alternatively, the hydrogenase system in macroscopic algae may be primarily a hydrogen-uptake system with respect to light-activated reactions. A simple kinetic argument based on recent measurements of the photosynthetic turnover times of simultaneous light-activated hydrogen and oxygen production is presented that supports the second explanation. 25 references, 3 figures, 1 table.« less

Enhanced muscular oxygen extraction in athletes exaggerates hypoxemia during exercise in hypoxia.

PubMed

Van Thienen, Ruud; Hespel, Peter

2016-02-01

High rate of muscular oxygen utilization facilitates the development of hypoxemia during exercise at altitude. Because endurance training stimulates oxygen extraction capacity, we investigated whether endurance athletes are at higher risk to developing hypoxemia and thereby acute mountain sickness symptoms during exercise at simulated high altitude. Elite athletes (ATL; n = 8) and fit controls (CON; n = 7) cycled for 20 min at 100 W (EX100W), as well as performed an incremental maximal oxygen consumption test (EXMAX) in normobaric hypoxia (0.107 inspired O2 fraction) or normoxia (0.209 inspired O2 fraction). Cardiorespiratory responses, arterial Po2 (PaO2), and oxygenation status in m. vastus lateralis [tissue oxygenation index (TOIM)] and frontal cortex (TOIC) by near-infrared spectroscopy, were measured. Muscle O2 uptake rate was estimated from change in oxyhemoglobin concentration during a 10-min arterial occlusion in m. gastrocnemius. Maximal oxygen consumption in normoxia was 70 ± 2 ml·min(-1·)kg(-1) in ATL vs. 43 ± 2 ml·min(-1·)kg(-1) in CON, and in hypoxia decreased more in ATL (-41%) than in CON (-25%, P < 0.05). Both in normoxia at PaO2 of ∼95 Torr, and in hypoxia at PaO2 of ∼35 Torr, muscle O2 uptake was twofold higher in ATL than in CON (0.12 vs. 0.06 ml·min(-1)·100 g(-1); P < 0.05). During EX100W in hypoxia, PaO2 dropped to lower (P < 0.05) values in ATL (27.6 ± 0.7 Torr) than in CON (33.5 ± 1.0 Torr). During EXMAX, but not during EX100W, TOIM was ∼15% lower in ATL than in CON (P < 0.05). TOIC was similar between the groups at any time. This study shows that maintenance of high muscular oxygen extraction rate at very low circulating PaO2 stimulates the development of hypoxemia during submaximal exercise in hypoxia in endurance-trained individuals. This effect may predispose to premature development of acute mountain sickness symptoms during exercise at altitude. Copyright © 2016 the American Physiological Society.

Uptake of Small Organic Compounds by Sulfuric Acid Aerosols: Dissolution and Reaction

NASA Technical Reports Server (NTRS)

Iraci, L. T.; Michelsen, R. R.; Ashbourn, S. F. M.; Staton, S. J. R.

2003-01-01

To assess the role of oxygenated volatile organic compounds in the upper troposphere and lower stratosphere, the interactions of a series of small organic compounds with low-temperature aqueous sulfuric acid will be evaluated. The total amount of organic material which may be taken up from the gas phase by dissolution, surface layer formation, and reaction during the particle lifetime will be quantified. Our current results for acetaldehyde uptake on 40 - 80 wt% sulfuric acid solutions will be compared to those of methanol, formaldehyde, and acetone to investigate the relationships between chemical functionality and heterogeneous activity. Where possible, equilibrium uptake will be ascribed to component pathways (hydration, protonation, etc.) to facilitate evaluation of other species not yet studied in low temperature aqueous sulfuric acid.

The effect and biological mechanism of granular sludge size on performance of autotrophic nitrogen removal system.

PubMed

Ya-Juan, Xing; Jun-Yuan, Ji; Ping, Zheng; Lan, Wang; Abbas, Ghulam; Zhang, Jiqiang; Ru, Wang; Zhan-Fei, He

2018-05-31

The autotrophic process for nitrogen removal has attracted worldwide attention in the field of wastewater treatment, and the performance of this process is greatly influenced by the size of granular sludge particles present in the system. In this work, the granular sludge was divided into three groups, i.e. large size (> 1.2 mm), medium size (0.6-1.2 mm) and small size (< 0.6 mm). The medium granular sludge was observed to dominate at high volumetric nitrogen loading rates, while offering strong support for good performance. Its indispensable contribution was found to originate from improved settling velocity (0.84 ± 0.10 cm/s), high SOUR-A (specific oxygen uptake rate for ammonia oxidizing bacteria, 25.93 mg O 2 /g MLVSS/h), low SOUR-N (specific oxygen uptake rate for nitrite oxidizing bacteria, 3.39 mg O 2 /g MLVSS/h), and a reasonable microbial spatial distribution.

Changes in cardiopulmonary function in normal adults after the Rockport 1 mile walking test: a preliminary study.

PubMed

Kim, Kyoung; Lee, Hye-Young; Lee, Do-Youn; Nam, Chan-Woo

2015-08-01

[Purpose] The purpose of this study was to investigate the changes of cardiopulmonary function in normal adults after the Rockport 1 mile walking test. [Subjects and Methods] University students (13 males and 27 females) participated in this study. Before and after the Rockport 1 mile walking test, pulmonary function, respiratory pressure, and maximal oxygen uptake were measured. [Results] Significant improvements in forced vital capacity and maximal inspiratory pressure were observed after the Rockport 1 mile walking test in males, and significant improvements in forced vital capacity, forced expiratory volume at 1 s, maximal inspiratory pressure, and maximal expiratory pressure were observed after the Rockport 1 mile walking test in females. However, the maximal oxygen uptake was not significantly different. [Conclusion] Our findings indicate that the Rockport 1 mile walking test changes cardiopulmonary function in males and females, and that it may improve cardiopulmonary function in middle-aged and older adults and provide basic data on cardiopulmonary endurance.

Changes in cardiopulmonary function in normal adults after the Rockport 1 mile walking test: a preliminary study

PubMed Central

Kim, Kyoung; Lee, Hye-Young; Lee, Do-Youn; Nam, Chan-Woo

2015-01-01

[Purpose] The purpose of this study was to investigate the changes of cardiopulmonary function in normal adults after the Rockport 1 mile walking test. [Subjects and Methods] University students (13 males and 27 females) participated in this study. Before and after the Rockport 1 mile walking test, pulmonary function, respiratory pressure, and maximal oxygen uptake were measured. [Results] Significant improvements in forced vital capacity and maximal inspiratory pressure were observed after the Rockport 1 mile walking test in males, and significant improvements in forced vital capacity, forced expiratory volume at 1 s, maximal inspiratory pressure, and maximal expiratory pressure were observed after the Rockport 1 mile walking test in females. However, the maximal oxygen uptake was not significantly different. [Conclusion] Our findings indicate that the Rockport 1 mile walking test changes cardiopulmonary function in males and females, and that it may improve cardiopulmonary function in middle-aged and older adults and provide basic data on cardiopulmonary endurance. PMID:26356048

Growth determinations for unattached bacteria in a contaminated aquifer.

USGS Publications Warehouse

Harvey, R.W.; George, L.H.

1987-01-01

Growth rates of unattached bacteria in groundwater contaminated with treated sewage and collected at various distances from the source of contamination were estimated by using frequency of dividing cells and tritiated-thymidine uptake and compared with growth rates obtained with unsupplemented, closed-bottle incubations. Estimates of bacterial generation times [(In 2)/mu] along a 3-km-long transect in oxygen-depleted (0.1 to 0.7 mg of dissolved oxygen liter-1) groundwater ranged from 16 h at 0.26 km downgradient from an on-land, treated-sewage outfall to 139 h at 1.6 km and correlated with bacterial abundance (r2 = 0.88 at P less than 0.001). Partitioning of assimilated thymidine into nucleic acid generally decreased with distance from the contaminant source, and one population in heavily contaminated groundwater assimilated little thymidine during a 20-h incubation. Several assumptions commonly made when frequency of dividing cells and tritiated-thymidine uptake are used were not applicable to the groundwater samples.

Cost of ventilation and effect of digestive state on the ventilatory response of the tegu lizard.

PubMed

Skovgaard, Nini; Wang, Tobias

2004-07-12

We performed simultaneous measurements of ventilation, oxygen uptake and carbon dioxide production in the South American lizard, Tupinambis merianae, equipped with a mask and maintained at 25 degrees C. Ventilation of resting animals was stimulated by progressive exposure to hypercapnia (2, 4 and 6%) or hypoxia (15, 10, 8 and 6%) in inspired gas mixture. This was carried out in both fasting and digesting animals. The ventilatory response to hypercapnia and hypoxia were affected by digestive state, with a more vigorous ventilatory response in digesting animals compared to fasting animals. Hypoxia doubled total ventilation while hypercapnia led to a four-fold increase in total ventilation both accomplished through an increase in tidal volume. Oxygen uptake remained constant during all hypercapnic exposures while there was an increase during hypoxia. Cost of ventilation was estimated to be 17% during hypoxia but less than 1% during hypercapnia. Our data indicate that ventilation can be greatly elevated at a small energetic cost.

Deuterium uptake and sputtering of simultaneous lithiated, boronized, and oxidized carbon surfaces irradiated by low-energy deuterium

NASA Astrophysics Data System (ADS)

Domínguez-Gutiérrez, F. J.; Krstić, P. S.; Allain, J. P.; Bedoya, F.; Islam, M. M.; Lotfi, R.; van Duin, A. C. T.

2018-05-01

We study the effects of deuterium irradiation on D-uptake by simultaneously boronized, lithiated, oxidized, and deuterated carbon surfaces. We present analysis of the bonding chemistry of D for various concentrations of boron, lithium, oxygen, and deuterium on carbon surfaces using molecular dynamics with reactive force field potentials, which are here adapted to include the interaction of boron and lithium. We calculate D retention and sputtering yields of each constituent of the Li-C-B-O mixture and discuss the role of oxygen in these processes. The extent of the qualitative agreement between new experimental data for B-C-O-D obtained in this paper and computational data is provided. As in the case of the Li-C-O system, comparative studies where experimental and computational data complement each other (in this case on the B-Li-C-O system) provide deeper insights into the mechanisms behind the role that O plays in the retention of D, a relevant issue in fusion machines.

CKM Gene G (Ncoi-) Allele Has a Positive Effect on Maximal Oxygen Uptake in Caucasian Women Practicing Sports Requiring Aerobic and Anaerobic Exercise Metabolism

PubMed Central

Gronek, Piotr; Holdys, Joanna; Kryściak, Jakub; Stanisławski, Daniel

2013-01-01

The search for genes with a positive influence on physical fitness is a difficult process. Physical fitness is a trait determined by multiple genes, and its genetic basis is then modified by numerous environmental factors. The present study examines the effects of the polymorphism of creatine kinase (CKM) gene on VO2max – a physiological index of aerobic capacity of high heritability. The study sample consisted of 154 men and 85 women, who were students of the University School of Physical Education in Poznań and athletes practicing various sports, including members of the Polish national team. The study revealed a positive effect of a rare G (NcoI−) allele of the CKM gene on maximal oxygen uptake in Caucasian women practicing sports requiring aerobic and anaerobic exercise metabolism. Also a tendency was noted in individuals with NcoI−/− (GG) and NcoI−/+ (GA) genotypes to reach higher VO2max levels. PMID:24511349

Biomass characterization by dielectric monitoring of viability and oxygen uptake rate measurements in a novel membrane bioreactor.

PubMed

Shariati, Farshid Pajoum; Heran, Marc; Sarrafzadeh, Mohammad Hossein; Mehrnia, Mohammad Reza; Sarzana, Gabriele; Ghommidh, Charles; Grasmick, Alain

2013-07-01

The application of permittivity and oxygen uptake rate (OUR) as biological process control parameters in a wastewater treatment system was evaluated. Experiments were carried out in a novel airlift oxidation ditch membrane bioreactor under different organic loading rates (OLR). Permittivity as representative of activated sludge viability was measured by a capacitive on-line sensor. OUR was also measured as a representative for respirometric activity. Results showed that the biomass concentration increases with OLR and all biomass related measurements and simulators such as MLSS, permittivity, OUR, ASM1 and ASM3 almost follow the same increasing trends. The viability of biomass decreased when the OLR was reduced from 5 to 4 kg COD m(-3)d(-1). During decreasing of OLR, biomass related parameters generally decreased but not in a similar manner. Also, protein concentration in the system during OLR decreasing changed inversely with the activated sludge viability. Copyright © 2013 Elsevier Ltd. All rights reserved.

Influence of colorant and film thickness on thermal aging characteristics of oxo-biodegradable plastic bags

NASA Astrophysics Data System (ADS)

Leuterio, Giselle Lou D.; Pajarito, Bryan B.; Domingo, Carla Marie C.; Lim, Anna Patricia G.

2016-05-01

Functional, lightweight, strong and cheap plastic bags incorporated with pro-oxidants undergo accelerated degradation under exposure to heat and oxygen. This work investigated the effect of colorant and film thickness on thermal aging characteristics of commercial oxo-biodegradable plastic bag films at 70 °C. Degradation is monitored through changes in infrared absorption, weight, and tensile properties of thermally aged films. The presence of carbonyl band in infrared spectrum after 672 h of thermal aging supports the degradation behavior of exposed films. Results show that incorporation of colorant and increasing thickness exhibit low maximum weight uptake. Titanium dioxide as white colorant in films lowers the susceptibility of films to oxygen uptake but enhances physical degradation. Higher amount of pro-oxidant loading also contributes to faster degradation. Opaque films are characterized by low tensile strength and high elastic modulus. Decreasing the thickness contributes to lower tensile strength of films. Thermally aged films with colorant and low thickness promote enhanced degradation.

Physical fitness, menstrual cycle disorders and smoking habit in Croatian National Ballet and National Folk Dance Ensembles.

PubMed

Oreb, Goran; Ruzić, Lana; Matković, Branka; Misigoj-Duraković, Marjeta; Vlasić, Jadranka; Ciliga, Dubravka

2006-06-01

The study investigated differences in morphological, motor and functional abilities between folk and ballet dancers. The sample comprised 51 female subjects: Croatian National Ballet (N=30) and Croatian National Folk Ensemble "LADO" (N=21). The data regarding menstrual cycle, menarche, number of births and smoking habit were collected and the morphological, motor and functional abilities measured. Significant correlations between the amount of fat tissue and number of births were found in both groups. Folk dancers were as tall as ballet dancers but weighted more and had a larger body frame (p<0.001). Ballet dancers were more flexible but there were no differences in absolute maximal oxygen uptake (2.65 vs. 2.35 L/min, p=0.101). Still, as the ballet dancers weighted less, their relative maximal oxygen uptake was significantly higher (37.62 vs. 50.22 mL/kg/min, p<0.001). Also, a high number of 45% of smokers among professional ballet and professional folk dancers was found.

Quantification of the impact of macrophytes on oxygen dynamics and nitrogen retention in a vegetated lowland river

NASA Astrophysics Data System (ADS)

Desmet, N. J. S.; Van Belleghem, S.; Seuntjens, P.; Bouma, T. J.; Buis, K.; Meire, P.

When macrophytes are growing in the river, the vegetation induces substantial changes to the water quality. Some effects are the result of direct interactions, such as photosynthetic activity or nutrient uptake, whereas others may be attributed to indirect effects of the water plants on hydrodynamics and river processes. This research focused on the direct effect of macrophytes on oxygen dynamics and nutrient cycling. Discharge, macrophyte biomass density, basic water quality, dissolved oxygen and nutrient concentrations were in situ monitored throughout the year in a lowland river (Nete catchment, Belgium). In addition, various processes were investigated in more detail in multiple ex situ experiments. The field and aquaria measurement results clearly demonstrated that aquatic plants can exert considerable impact on dissolved oxygen dynamics in a lowland river. When the river was dominated by macrophytes, dissolved oxygen concentrations varied from 5 to 10 mg l -1. Considering nutrient retention, it was shown that the investigated in-stream macrophytes could take up dissolved inorganic nitrogen (DIN) from the water column at rates of 33-50 mg N kgdry matter-1 h. And DIN fluxes towards the vegetation were found to vary from 0.03 to 0.19 g N ha -1 h -1 in spring and summer. Compared to the measured changes in DIN load over the river stretch, it means that about 3-13% of the DIN retention could be attributed to direct nitrogen uptake from the water by macrophytes. Yet, the role of macrophytes in rivers should not be underrated as aquatic vegetation also exerts considerable indirect effects that may have a greater impact than the direct fixation of nutrients into the plant biomass.

A comparison of methods to estimate anaerobic capacity: Accumulated oxygen deficit and W' during constant and all-out work-rate profiles.

PubMed

Muniz-Pumares, Daniel; Pedlar, Charles; Godfrey, Richard; Glaister, Mark

2017-12-01

This study investigated (i) whether the accumulated oxygen deficit (AOD) and curvature constant of the power-duration relationship (W') are different during constant work-rate to exhaustion (CWR) and 3-min all-out (3MT) tests and (ii) the relationship between AOD and W' during CWR and 3MT. Twenty-one male cyclists (age: 40 ± 6 years; maximal oxygen uptake [V̇O 2max ]: 58 ± 7 ml · kg -1 · min -1 ) completed preliminary tests to determine the V̇O 2 -power output relationship and V̇O 2max . Subsequently, AOD and W' were determined as the difference between oxygen demand and oxygen uptake and work completed above critical power, respectively, in CWR and 3MT. There were no differences between tests for duration, work, or average power output (P ≥ 0.05). AOD was greater in the CWR test (4.18 ± 0.95 vs. 3.68 ± 0.98 L; P = 0.004), whereas W' was greater in 3MT (9.55 ± 4.00 vs. 11.37 ± 3.84 kJ; P = 0.010). AOD and W' were significantly correlated in both CWR (P < 0.001, r = 0.654) and 3MT (P < 0.001, r = 0.654). In conclusion, despite positive correlations between AOD and W' in CWR and 3MT, between-test differences in the magnitude of AOD and W', suggest that both measures have different underpinning mechanisms.

Process optimization involving critical evaluation of oxygen transfer, oxygen uptake and nitrogen limitation for enhanced biomass and lipid production by oleaginous yeast for biofuel application.

PubMed

Chopra, Jayita; Sen, Ramkrishna

2018-04-20

Lipid accumulation in oleaginous yeast is generally induced by nitrogen starvation, while oxygen saturation can influence biomass growth. Systematic shake flask studies that help in identifying the right nitrogen source and relate its uptake kinetics to lipid biosynthesis under varying oxygen saturation conditions are very essential for addressing the bioprocessing-related issues, which are envisaged to occur in the fermenter scale production. In the present study, lipid bioaccumulation by P. guilliermondii at varying C:N ratios and oxygen transfer conditions (assessed in terms of k L a) was investigated in shake flasks using a pre-optimized N-source and a two-stage inoculum formulated in a hybrid medium. A maximum lipid concentration of 10.8 ± 0.5 g L -1 was obtained in shake flask study at the optimal condition with an initial C:N and k L a of 60:1 and 0.6 min -1 , respectively, at a biomass specific growth rate of 0.11 h -1 . Translating these optimal shake flask conditions to a 3.7 L stirred tank reactor resulted in biomass and lipid concentrations of 16.74 ± 0.8 and 8 ± 0.4 g L -1 . The fatty acid methyl ester (FAME) profile of lipids obtained by gas chromatography was found to be suitable for biodiesel application. We strongly believe that the rationalistic approach-based design of experiments adopted in the study would help in achieving high cell density with improved lipid accumulation and also minimize the efforts towards process optimization during bioreactor level operations, consequently reducing the research and development-associated costs.

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

Khadjavi, Amina; Magnetto, Chiara; Panariti, Alice

Background: : In chronic wounds, efficient epithelial tissue repair is hampered by hypoxia, and balances between the molecules involved in matrix turn-over such as matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are seriously impaired. Intriguingly, new oxygenating nanocarriers such as 2H,3H-decafluoropentane-based oxygen-loaded nanodroplets (OLNs) might effectively target chronic wounds. Objective: : To investigate hypoxia and chitosan-shelled OLN effects on MMP/TIMP production by human keratinocytes. Methods: : HaCaT cells were treated for 24 h with 10% v/v OLNs both in normoxia or hypoxia. Cytotoxicity and cell viability were measured through biochemical assays; cellular uptake by confocal microscopy; and MMPmore » and TIMP production by enzyme-linked immunosorbent assay or gelatin zymography. Results: : Normoxic HaCaT cells constitutively released MMP-2, MMP-9, TIMP-1 and TIMP-2. Hypoxia strongly impaired MMP/TIMP balances by reducing MMP-2, MMP-9, and TIMP-2, without affecting TIMP-1 release. After cellular uptake by keratinocytes, nontoxic OLNs abrogated all hypoxia effects on MMP/TIMP secretion, restoring physiological balances. OLN abilities were specifically dependent on time-sustained oxygen diffusion from OLN core. Conclusion: : Chitosan-shelled OLNs effectively counteract hypoxia-dependent dysregulation of MMP/TIMP balances in human keratinocytes. Therefore, topical administration of exogenous oxygen, properly encapsulated in nanodroplet formulations, might be a promising adjuvant approach to promote healing processes in hypoxic wounds. - Highlights: • Hypoxia impairs MMP9/TIMP1 and MMP2/TIMP2 balances in HaCaT human keratinocytes. • Chitosan-shelled oxygen-loaded nanodroplets (OLNs) are internalised by HaCaT cells. • OLNs are not toxic to HaCaT cells. • OLNs effectively counteract hypoxia effects on MMP/TIMP balances in HaCaT cells. • OLNs appear as promising and cost-effective therapeutic tools for hypoxic wounds.« less

The effect of exercise intensity and excess postexercise oxygen consumption on postprandial blood lipids in physically inactive men.

PubMed

Littlefield, Laurel A; Papadakis, Zacharias; Rogers, Katie M; Moncada-Jiménez, José; Taylor, J Kyle; Grandjean, Peter W

2017-09-01

Reductions in postprandial lipemia have been observed following aerobic exercise of sufficient energy expenditure. Increased excess postexercise oxygen consumption (EPOC) has been documented when comparing high- versus low-intensity exercise. The contribution of EPOC energy expenditure to alterations in postprandial lipemia has not been determined. The purpose of this study was to evaluate the effects of low- and high-intensity exercise on postprandial lipemia in healthy, sedentary, overweight and obese men (age, 43 ± 10 years; peak oxygen consumption, 31.1 ± 7.5 mL·kg -1 ·min -1 ; body mass index, 31.8 ± 4.5 kg/m 2 ) and to determine the contribution of EPOC to reductions in postprandial lipemia. Participants completed 4 conditions: nonexercise control, low-intensity exercise at 40%-50% oxygen uptake reserve (LI), high-intensity exercise at 70%-80% oxygen uptake reserve (HI), and HI plus EPOC re-feeding (HI+EERM), where the difference in EPOC energy expenditure between LI and HI was re-fed in the form of a sports nutrition bar (Premier Nutrition Corp., Emeryville, Calif., USA). Two hours following exercise participants ingested a high-fat (1010 kcals, 99 g sat fat) test meal. Blood samples were obtained before exercise, before the test meal, and at 2, 4, and 6 h postprandially. Triglyceride incremental area under the curve was significantly reduced following LI, HI, and HI+EERM when compared with nonexercise control (p < 0.05) with no differences between the exercise conditions (p > 0.05). In conclusions, prior LI and HI exercise equally attenuated postprandial triglyceride responses to the test meal. The extra energy expended during EPOC does not contribute significantly to exercise energy expenditure or to reductions in postprandial lipemia in overweight men.

Oxygen interaction with disordered and nanostructured Ag(001) surfaces

NASA Astrophysics Data System (ADS)

Vattuone, L.; Burghaus, U.; Savio, L.; Rocca, M.; Costantini, G.; Buatier de Mongeot, F.; Boragno, C.; Rusponi, S.; Valbusa, U.

2001-08-01

We investigated O2 adsorption on Ag(001) in the presence of defects induced by Ne+ sputtering at different crystal temperatures, corresponding to different surface morphologies recently identified by scanning tunneling microscopy. The gas-phase molecules were dosed with a supersonic molecular beam. The total sticking coefficient and the total uptake were measured with the retarded reflector method, while the adsorption products were characterized by high resolution electron energy loss spectroscopy. We find that, for the sputtered surfaces, both sticking probability and total O2 uptake decrease. Molecular adsorption takes place also for heavily damaged surfaces but, contrary to the flat surface case, dissociation occurs already at a crystal temperature, T, of 105 K. The internal vibrational frequency of the O2 admolecules indicates that two out of the three O2- moieties present on the flat Ag(001) surface are destabilized by the presence of defects. The dissociation probability depends on surface morphology and drops for sputtering temperatures larger than 350 K, i.e., when surface mobility prevails healing the defects. The latter, previously identified with kink sites, are saturated at large O2 doses. The vibrational frequency of the oxygen adatoms, produced by low temperature dissociation, indicates the formation of at least two different adatom moieties, which we tentatively assign to oxygen atoms at kinks and vacancies.

Synthesis and in vitro phototoxicity of multifunctional Zn(II)meso-tetrakis(4-carboxyphenyl)porphyrin-coated gold nanoparticles assembled via axial coordination with imidazole ligands.

PubMed

Alea-Reyes, María E; Penon, Oriol; García Calavia, Paula; Marín, María J; Russell, David A; Pérez-García, Lluïsa

2018-07-01

Metalloporphyrins are extensively investigated for their ability to form reactive oxygen species and as potent photosensitisers for use in photodynamic therapy. However, their hydrophobicity generally causes solubility issues concerning in vivo delivery due to lack of distribution and low clearance from the body. Immobilising porphyrins on carriers, such as gold nanoparticles (GNP), can overcome some of these drawbacks. The mode of assembling the porphyrins to the carrier influences the properties of the resulting drug delivery systems. We describe the synthesis and characterisation of new porphyrin decorated water soluble GNP and we explore Zn-imidazole axial coordination as the mode of linking the porphyrin to the metallic core of the nanoparticles. Quantification of singlet oxygen production, toxicity in dark, cellular uptake by SK-BR-3 cells and phototoxicity have been assessed. Axial coordination limits the number of porphyrins on the gold surface, reduces the formation of aggregates, and diminishes metal exchange in the porphyrin, all of which contribute to enhance the efficiency of singlet oxygen generation from the immobilised porphyrin. In vitro experiments on SK-BR-3 cells reveal a fast uptake followed by more than 80% cell death after irradiation with low doses of light. Copyright © 2018 Elsevier Inc. All rights reserved.

Integration of Carbon, Nitrogen, and Oxygen Metabolism in Escherichia coli--Final Report

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

Rabinowitz, Joshua D; Wingreen, Ned s; Rabitz, Herschel A

2012-10-22

A key challenge for living systems is balancing utilization of multiple elemental nutrients, such as carbon, nitrogen, and oxygen, whose availability is subject to environmental fluctuations. As growth can be limited by the scarcity of any one nutrient, the rate at which each nutrient is assimilated must be sensitive not only to its own availability, but also to that of other nutrients. Remarkably, across diverse nutrient conditions, E. coli grows nearly optimally, balancing effectively the conversion of carbon into energy versus biomass. To investigate the link between the metabolism of different nutrients, we quantified metabolic responses to nutrient perturbations usingmore » LC-MS based metabolomics and built differential equation models that bridge multiple nutrient systems. We discovered that the carbonaceous substrate of nitrogen assimilation, -ketoglutarate, directly inhibits glucose uptake and that the upstream glycolytic metabolite, fructose-1,6-bisphosphate, ultrasensitively regulates anaplerosis to allow rapid adaptation to changing carbon availability. We also showed that NADH controls the metabolic response to changing oxygen levels. Our findings support a general mechanism for nutrient integration: limitation for a nutrient other than carbon leads to build-up of the most closely related product of carbon metabolism, which in turn feedback inhibits further carbon uptake.« less

Performance and physiological effects of different descending strategies for cross-country mountain biking.

PubMed

Miller, Matthew C; Macdermid, Paul W; Fink, Phil W; Stannard, Stephen R

2017-04-01

This study investigated the performance-related feasibility and physiological benefits of purposefully eliminating propulsive work while descending in mountain biking and compared values to those measured during road descending. Participants cycled uphill on a road at race pace before descending over three conditions (off-road pedalling; off-road coasting; road coasting). Relatively low power output during off-road pedalling was associated with a greater oxygen uptake (p < .01) when compared with off-road coasting despite no difference in vibration exposure (p > .05). Importantly, pedalling did not invoke a performance benefit (p > .05) on the descent used in this study. Significantly greater heart rate and oxygen uptake (both p < .01) were observed between road and off-road descending, likely caused by the increase in terrain-induced vibrations (p < .01) experienced between the bicycle and rider. Results indicate that reducing propulsive work during descending can improve recovery without being disadvantageous to performance. Similarly, the vibrations experienced during road descending are relatively low, and further reduce oxygen cost. In an effort to increase efficiency, it is recommended that mountain bike athletes focus on skills to increase descending speed without the addition of pedalling, and that equipment be used to decrease vibrations nearer to those seen on the road.

Copper transport into the secretory pathway is regulated by oxygen in macrophages

PubMed Central

White, Carine; Kambe, Taiho; Fulcher, Yan G.; Sachdev, Sherri W.; Bush, Ashley I.; Fritsche, Kevin; Lee, Jaekwon; Quinn, Thomas P.; Petris, Michael J.

2009-01-01

Summary Copper is an essential nutrient for a variety of biochemical processes; however, the redox properties of copper also make it potentially toxic in the free form. Consequently, the uptake and intracellular distribution of this metal is strictly regulated. This raises the issue of whether specific pathophysiological conditions can promote adaptive changes in intracellular copper distribution. In this study, we demonstrate that oxygen limitation promotes a series of striking alterations in copper homeostasis in RAW264.7 macrophage cells. Hypoxia was found to stimulate copper uptake and to increase the expression of the copper importer, CTR1. This resulted in increased copper delivery to the ATP7A copper transporter and copper-dependent trafficking of ATP7A to cytoplasmic vesicles. Significantly, the ATP7A protein was required to deliver copper into the secretory pathway to ceruloplasmin, a secreted copperdependent enzyme, the expression and activity of which were stimulated by hypoxia. However, the activities of the alternative targets of intracellular copper delivery, superoxide dismutase and cytochrome c oxidase, were markedly reduced in response to hypoxia. Collectively, these findings demonstrate that copper delivery into the biosynthetic secretory pathway is regulated by oxygen availability in macrophages by a selective increase in copper transport involving ATP7A. PMID:19351718

Gas exchange kinetics following concentric-eccentric isokinetic arm and leg exercise.

PubMed

Drescher, U; Mookerjee, S; Steegmanns, A; Knicker, A; Hoffmann, U

2017-06-01

To evaluate the effects of exercise velocity (60, 150, 240deg∙s -1 ) and muscle mass (arm vs leg) on changes in gas exchange and arterio-venous oxygen content difference (avDO 2 ) following high-intensity concentric-eccentric isokinetic exercise. Fourteen subjects (26.9±3.1years) performed a 3×20-repetition isokinetic exercise protocol. Recovery beat-to-beat cardiac output (CO) and breath-by-breath gas exchange were recorded to determine post-exercise half-time (t 1/2 ) for oxygen uptake (V˙O 2 pulm), carbon dioxide output (V˙CO 2 pulm), and ventilation (V˙ E ). Significant differences of the t 1/2 values were identified between 60 and 150deg∙s -1 . Significant differences in the t 1/2 values were observed between V˙O 2 pulm and V˙CO 2 pulm and between V˙CO 2 pulm and V˙ E . The time to attain the first avDO 2 -peak showed significant differences between arm and leg exercise. The present study illustrates, that V˙O 2 pulm kinetics are distorted due to non-linear CO dynamics. Therefore, it has to be taken into account, that V˙O 2 pulm may not be a valuable surrogate for muscular oxygen uptake kinetics in the recovery phases. Copyright © 2017 Elsevier B.V. All rights reserved.

Oxygen-storage behavior and local structure in Ti-substituted YMnO{sub 3}

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

Levin, I., E-mail: igor.levin@nist.gov; Krayzman, V.; Vanderah, T.A.

Hexagonal manganates RMnO{sub 3} (R=Y, Ho, Dy) have been recently shown to exhibit oxygen-storage capacities promising for three-way catalysts, air-separation, and related technologies. Here, we demonstrate that Ti substitution for Mn can be used to chemically tune the oxygen-breathing properties of these materials towards practical applications. Specifically, Y(Mn{sub 1−x}Ti{sub x})O{sub 3} solid solutions exhibit facile oxygen absorption/desorption via reversible Ti{sup 3+}↔Ti{sup 4+} and Mn{sup 3+}↔Mn{sup 4+} reactions already in ambient air at ≈400 °C and ≈250 °C, respectively. On cooling, the oxidation of both cations is accompanied by oxygen uptake yielding a formula YMn{sup 3+}{sub 1−x-y}Mn{sup 4+}{sub y}Ti{sup 4+}{sub x}O{submore » 3+δ}. The presence of Ti promotes the oxidation of Mn{sup 3+} to Mn{sup 4+}, which is almost negligible for YMnO{sub 3} in air, thereby increasing the uptake of oxygen beyond that required for a given Ti{sup 4+} concentration. The reversibility of the redox reactions is limited by sluggish kinetics; however, the oxidation process continues, if slowly, even at room temperature. The extra oxygen atoms are accommodated by the large interstices within a triangular lattice formed by the [MnO{sub 5}] trigonal bipyramids. According to bond distances from Rietveld refinements using the neutron diffraction data, the YMnO{sub 3} structure features under-bonded Mn and even more severely under-bonded oxygen atoms that form the trigonal bases of the [MnO{sub 5}] bipyramids. The tensile bond strain around the 5-fold coordinated Mn site and the strong preference of Ti{sup 4+}(and Mn{sup 4+}) for higher coordination numbers likely provide driving forces for the oxidation reaction. Reverse Monte Carlo refinements of the local atomic displacements using neutron total scattering revealed how the excess oxygen atoms are accommodated in the structure by correlated local displacements of the host atoms. Large displacements of the under-bonded host oxygen atoms play a key part in this lattice-relaxation process, facilitating reversible exchange of significant amounts of oxygen with atmosphere. - Graphical abstract: Concurrent redox reactions involving Ti and Mn yield facile absorption/desorption of excess oxygen. - Highlights: • Concurrent redox reactions involving Ti and Mn yield oxygen absorption/desorption. • Excess oxygen is accommodated as interstitials via correlated atomic shifts. • Oxygen breathing is facilitated by the under-bonding of host Mn and O atoms.« less

The effect of oxygen tension on human articular chondrocyte matrix synthesis: Integration of experimental and computational approaches

PubMed Central

Li, S; Oreffo, ROC; Sengers, BG; Tare, RS

2014-01-01

Significant oxygen gradients occur within tissue engineered cartilaginous constructs. Although oxygen tension is an important limiting parameter in the development of new cartilage matrix, its precise role in matrix formation by chondrocytes remains controversial, primarily due to discrepancies in the experimental setup applied in different studies. In this study, the specific effects of oxygen tension on the synthesis of cartilaginous matrix by human articular chondrocytes were studied using a combined experimental-computational approach in a “scaffold-free” 3D pellet culture model. Key parameters including cellular oxygen uptake rate were determined experimentally and used in conjunction with a mathematical model to estimate oxygen tension profiles in 21-day cartilaginous pellets. A threshold oxygen tension (pO2 ≈ 8% atmospheric pressure) for human articular chondrocytes was estimated from these inferred oxygen profiles and histological analysis of pellet sections. Human articular chondrocytes that experienced oxygen tension below this threshold demonstrated enhanced proteoglycan deposition. Conversely, oxygen tension higher than the threshold favored collagen synthesis. This study has demonstrated a close relationship between oxygen tension and matrix synthesis by human articular chondrocytes in a “scaffold-free” 3D pellet culture model, providing valuable insight into the understanding and optimization of cartilage bioengineering approaches. Biotechnol. Bioeng. 2014;111: 1876–1885. PMID:24668194

Cardiopulmonary exercise testing early after stroke using feedback-controlled robotics-assisted treadmill exercise: test-retest reliability and repeatability.

PubMed

Stoller, Oliver; de Bruin, Eling D; Schindelholz, Matthias; Schuster-Amft, Corina; de Bie, Rob A; Hunt, Kenneth J

2014-10-11

Exercise capacity is seriously reduced after stroke. While cardiopulmonary assessment and intervention strategies have been validated for the mildly and moderately impaired populations post-stroke, there is a lack of effective concepts for stroke survivors suffering from severe motor limitations. This study investigated the test-retest reliability and repeatability of cardiopulmonary exercise testing (CPET) using feedback-controlled robotics-assisted treadmill exercise (FC-RATE) in severely motor impaired individuals early after stroke. 20 subjects (age 44-84 years, <6 month post-stroke) with severe motor limitations (Functional Ambulatory Classification 0-2) were selected for consecutive constant load testing (CLT) and incremental exercise testing (IET) within a powered exoskeleton, synchronised with a treadmill and a body weight support system. A manual human-in-the-loop feedback system was used to guide individual work rate levels. Outcome variables focussed on standard cardiopulmonary performance parameters. Relative and absolute test-retest reliability were assessed by intraclass correlation coefficients (ICC), standard error of the measurement (SEM), and minimal detectable change (MDC). Mean difference, limits of agreement, and coefficient of variation (CoV) were estimated to assess repeatability. Peak performance parameters during IET yielded good to excellent relative reliability: absolute peak oxygen uptake (ICC =0.82), relative peak oxygen uptake (ICC =0.72), peak work rate (ICC =0.91), peak heart rate (ICC =0.80), absolute gas exchange threshold (ICC =0.91), relative gas exchange threshold (ICC =0.88), oxygen cost of work (ICC =0.87), oxygen pulse at peak oxygen uptake (ICC =0.92), ventilation rate versus carbon dioxide output slope (ICC =0.78). For these variables, SEM was 4-13%, MDC 12-36%, and CoV 0.10-0.36. CLT revealed high mean differences and insufficient test-retest reliability for all variables studied. This study presents first evidence on reliability and repeatability for CPET in severely motor impaired individuals early after stroke using a feedback-controlled robotics-assisted treadmill. The results demonstrate good to excellent test-retest reliability and appropriate repeatability for the most important peak cardiopulmonary performance parameters. These findings have important implications for the design and implementation of cardiovascular exercise interventions in severely impaired populations. Future research needs to develop advanced control strategies to enable the true limit of functional exercise capacity to be reached and to further assess test-retest reliability and repeatability in larger samples.

A hybrid multibreath wash-in wash-out lung function quantification scheme in human subjects using hyperpolarized 3 He MRI for simultaneous assessment of specific ventilation, alveolar oxygen tension, oxygen uptake, and air trapping.

PubMed

Hamedani, Hooman; Kadlecek, Stephen; Xin, Yi; Siddiqui, Sarmad; Gatens, Heather; Naji, Joseph; Ishii, Masaru; Cereda, Maurizio; Rossman, Milton; Rizi, Rahim

2017-08-01

To present a method for simultaneous acquisition of alveolar oxygen tension (P A O 2 ), specific ventilation (SV), and apparent diffusion coefficient (ADC) of hyperpolarized (HP) gas in the human lung, allowing reinterpretation of the P A O 2 and SV maps to produce a map of oxygen uptake (R). An imaging scheme was designed with a series of identical normoxic HP gas wash-in breaths to measure ADC, SV, P A O 2 , and R in less than 2 min. Signal dynamics were fit to an iterative recursive model that regionally solved for these parameters. This measurement was successfully performed in 12 subjects classified in three healthy, smoker, and chronic obstructive pulmonary disease (COPD) cohorts. The overall whole lung ADC, SV, P A O 2 , and R in healthy, smoker, and COPD subjects was 0.20 ± 0.03 cm 2 /s, 0.39 ± 0.06,113 ± 2 Torr, and 1.55 ± 0.35 Torr/s, respectively, in healthy subjects; 0.21 ± 0.03 cm 2 /s, 0.33 ± 0.06, 115.9 ± 4 Torr, and 0.97 ± 0.2 Torr/s, respectively, in smokers; and 0.25 ± 0.06 cm 2 /s, 0.23 ± 0.08, 114.8 ± 6.0Torr, and 0.94 ± 0.12 Torr/s, respectively, in subjects with COPD. Hetrogeneity of SV, P A O 2 , and R were indicators of both smoking-related changes and disease, and the severity of the disease correlated with the degree of this heterogeneity. Subjects with symptoms showed reduced oxygen uptake and specific ventilation. High-resolution, nearly coregistered and quantitative measures of lung function and structure were obtained with less than 1 L of HP gas. This hybrid multibreath technique produced measures of lung function that revealed clear differences among the cohorts and subjects and were confirmed by correlations with global lung measurements. Magn Reson Med 78:611-624, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Oxygen uptake during functional activities after stroke—Reliability and validity of a portable ergospirometry system

PubMed Central

Brurok, Berit; Tjønna, Arnt Erik; Tørhaug, Tom; Askim, Torunn

2017-01-01

Background People with stroke have a low peak aerobic capacity and experience increased effort during performance of daily activities. The purpose of this study was to examine test-retest reliability of a portable ergospirometry system in people with stroke during performance of functional activities in a field-test. Secondary aims were to examine the proportion of oxygen consumed during the field-test in relation to the peak-test and to analyse the correlation between the oxygen uptake during the field-test and peak-test in order to support the validity of the field-test. Methods With simultaneous measurement of oxygen consumption, participants performed a standardized field-test consisting of five activities; walking over ground, stair walking, stepping over obstacles, walking slalom between cones and from a standing position lifting objects from one height to another. All activities were performed in self-selected speed. Prior to the field-test, a peak aerobic capacity test was performed. The field-test was repeated minimum 2 and maximum 14 days between the tests. ICC2,1 and Bland Altman tests (Limits of Agreement, LoA) were used to analyse test-retest reliability. Results In total 31 participants (39% women, mean (SD) age 54.5 (12.7) years and 21.1 (14.3) months’ post-stroke) were included. The ICC2,1 was ≥ 0.80 for absolute V̇O2, relative V̇O2, minute ventilation, CO2, respiratory exchange ratio, heart rate and Borgs rating of perceived exertion. ICC2,1 for total time to complete the field-test was 0.99. Mean difference in steady state V̇O2 during Test 1 and Test 2 was -0.40 (2.12) The LoAs were -3.75 and 4.51. Participants spent 60.7% of their V̇O2peak performing functional activities. Correlation between field-test and peak-test was 0.689, p = 0.001 for absolute and 0.733, p = 0.001 for relative V̇O2. Conclusions This study presents first evidence on reliability of oxygen uptake during performance of functional activities after stroke, showing very good test-retest reliability. The secondary analysis showed that the amount of energy spent during the field-test relative to the peak-test was high and the correlation between the two test was good, supporting the validity of this method. PMID:29065164

Dual organism design cycle reveals small subunit substitutions that improve [NiFe] hydrogenase hydrogen evolution.

PubMed

Yonemoto, Isaac T; Matteri, Christopher W; Nguyen, Thao Amy; Smith, Hamilton O; Weyman, Philip D

2013-07-02

Photosynthetic microorganisms that directly channel solar energy to the production of molecular hydrogen are a potential future biofuel system. Building such a system requires installation of a hydrogenase in the photosynthetic organism that is both tolerant to oxygen and capable of hydrogen production. Toward this end, we have identified the [NiFe] hydrogenase from the marine bacterium Alteromonas macleodii "Deep ecotype" that is able to be heterologously expressed in cyanobacteria and has tolerance to partial oxygen. The A. macleodii enzyme shares sequence similarity with the uptake hydrogenases that favor hydrogen uptake activity over hydrogen evolution. To improve hydrogen evolution from the A. macleodii hydrogenase, we examined the three Fe-S clusters found in the small subunit of many [NiFe] uptake hydrogenases that presumably act as a molecular wire to guide electrons to or from the active site of the enzyme. Studies by others altering the medial cluster of a Desulfovibrio fructosovorans hydrogenase from 3Fe-4S to 4Fe-4S resulted in two-fold improved hydrogen evolution activity. We adopted a strategy of screening for improved hydrogenase constructs using an Escherichia coli expression system before testing in slower growing cyanobacteria. From the A. macleodii enzyme, we created a mutation in the gene encoding the hydrogenase small subunit that in other systems is known to convert the 3Fe-4S medial cluster to 4Fe-4S. The medial cluster substitution did not improve the hydrogen evolution activity of our hydrogenase. However, modifying both the medial cluster and the ligation of the distal Fe-S cluster improved in vitro hydrogen evolution activity relative to the wild type hydrogenase by three- to four-fold. Other properties of the enzyme including thermostability and tolerance to partial oxygen did not appear to be affected by the substitutions. Our results show that substitution of amino acids altering the ligation of Fe-S clusters in the A. macleodii [NiFe] uptake hydrogenase resulted in increased hydrogen evolution activity. This activity can be recapitulated in multiple host systems and with purified protein. These results validate the approach of using an E. coli-cyanobacteria shuttle system for enzyme expression and improvement.

Biochemistry of free radicals: from electrons to tissues.

PubMed

Boveris, A

1998-01-01

Free radicals are chemical species with an unpaired electron in the outer valence orbitals. The unpaired electron makes them paramagnetic (physics) and relatively reactive (chemistry). The free radicals that are normal metabolites in aerobic biological systems have varied reactivities, ranging from the high reactivity of hydroxyl radical (t1/2 = 10(-9) s) to the low reactivity of melanins (t1/2 = days). The univalent reduction of oxygen that takes place in mammalian organs produces superoxide radicals at a rate of about 2% of the total oxygen uptake. The primary production of superoxide radicals sustains a free radical chain reaction involving a series of reactive oxygen species (hydrogen peroxide, hydroxyl and peroxyl radical and singlet oxygen). Nitric oxide is almost unreactive as free radical except for its termination reaction with superoxide radical to yield the strong oxidant peroxynitrite. Nitric oxide also reacts with ubiquinol in a redox reaction, with cytochrome oxidase competitively with oxygen, and oxymyoglobin and oxyhemoglobin displacing oxygen. Septic shock and endotoxemia produce muscle dysfunction and oxidative stress due to increased steady state concentrations of reactive oxygen and nitrogen species.

Radiation increases the cellular uptake of exosomes through CD29/CD81 complex formation

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

Hazawa, Masaharu; Tomiyama, Kenichi; Saotome-Nakamura, Ai

Highlights: • Radiation increases cellular uptake of exosomes. • Radiation induces colocalization of CD29 and CD81. • Exosomes selectively bind the CD29/CD81 complex. • Radiation increases the cellular uptake of exosomes through CD29/CD81 complex formation. - Abstract: Exosomes mediate intercellular communication, and mesenchymal stem cells (MSC) or their secreted exosomes affect a number of pathophysiologic states. Clinical applications of MSC and exosomes are increasingly anticipated. Radiation therapy is the main therapeutic tool for a number of various conditions. The cellular uptake mechanisms of exosomes and the effects of radiation on exosome–cell interactions are crucial, but they are not well understood.more » Here we examined the basic mechanisms and effects of radiation on exosome uptake processes in MSC. Radiation increased the cellular uptake of exosomes. Radiation markedly enhanced the initial cellular attachment to exosomes and induced the colocalization of integrin CD29 and tetraspanin CD81 on the cell surface without affecting their expression levels. Exosomes dominantly bound to the CD29/CD81 complex. Knockdown of CD29 completely inhibited the radiation-induced uptake, and additional or single knockdown of CD81 inhibited basal uptake as well as the increase in radiation-induced uptake. We also examined possible exosome uptake processes affected by radiation. Radiation-induced changes did not involve dynamin2, reactive oxygen species, or their evoked p38 mitogen-activated protein kinase-dependent endocytic or pinocytic pathways. Radiation increased the cellular uptake of exosomes through CD29/CD81 complex formation. These findings provide essential basic insights for potential therapeutic applications of exosomes or MSC in combination with radiation.« less

Effect of bottom water oxygenation on oxygen consumption and benthic biogeochemical processes at the Crimean Shelf (Black Sea)

NASA Astrophysics Data System (ADS)

Lichtschlag, A.; Janssen, F.; Wenzhöfer, F.; Holtappels, M.; Struck, U.; Jessen, G.; Boetius, A.

2012-04-01

Hypoxia occurs where oxygen concentrations fall below a physiological threshold of many animals, usually defined as <63 µmol L-1. Oxygen depletion can be caused by anthropogenic influences, such as global warming and eutrophication, but as well occurs naturally due to restricted water exchange in combination with high nutrient loads (e.g. upwelling). Bottom-water oxygen availability not only influences the composition of faunal communities, but is also one of the main factors controlling sediment-water exchange fluxes and organic carbon degradation in the sediment, usually shifting processes towards anaerobic mineralization pathways mediated by microorganisms. The Black Sea is one of the world's largest meromictic marine basins with an anoxic water column below 180m. The outer shelf edge, where anoxic waters meet the seafloor, is an ideal natural laboratory to study the response of benthic ecosystems to hypoxia, including benthic biogeochemical processes. During the MSM 15/1 expedition with the German research vessel MARIA S. MERIAN, the NW area of the Black Sea (Crimean Shelf) was studied. The study was set up to investigate the influence of bottom water oxygenation on, (1) the respective share of fauna-mediated oxygen uptake, microbial respiration, or re-oxidation of reduced compounds formed in the deeper sediments for the total oxygen flux and (2) on the efficiency of benthic biogeochemical cycles. During our study, oxygen consumption and pathways of organic carbon degradation were estimated from benthic chamber incubations, oxygen microprofiles measured in situ, and pore water and solid phase profiles measured on retrieved cores under oxic, hypoxic, and anoxic water column conditions. Benthic oxygen fluxes measured in Crimean Shelf sediments in this study were comparable to fluxes from previous in situ and laboratory measurements at similar oxygen concentrations (total fluxes -8 to -12 mmol m-2 d-1; diffusive fluxes: -2 to -5 mmol m-2 d-1) with oxygen penetrating less than 5 mm into the seafloor. In total oxygen uptake by the seafloor, the fraction of the diffusive flux, which comprises microbial consumption plus re-oxidation of reduced compounds, increased with declining oxygen concentrations. Measurements and modeling of penetration depths and fluxes of the electron acceptors nitrate, iron- and manganese oxides, sulfate suggest that as long as oxygen is available in the oxic and the hypoxic zones of the Crimean shelf, the largest fraction of oxygen is consumed directly during aerobic mineralization of organic matter and re-oxidation processes play only a minor role. Furthermore, the combination of rapid and strong fluctuation of bottom water oxygen concentration and low sedimentation rates appear to repress anaerobic organic matter degradation. This study was carried out within the framework of the EU-funded project HYPOX (www.hypox.net), which is set up to improve our understanding of hypoxia formation and to develop capacities and know-how for hypoxia monitoring.

FDG PET Imaging in Pneumocystis Pneumonia.

PubMed

Kono, Masanori; Yamashita, Hiroyuki; Kubota, Kazuo; Kano, Toshikazu; Mimori, Akio

2015-08-01

A 69-year-old woman with rheumatoid arthritis and pleuritis presented with dyspnea. On admission, she was afebrile and had an oxygen saturation of 97% on ambient air. Chest radiography and CT revealed only subtle ground-glass opacities. However, FDG PET revealed pathological uptake in both lungs. A diagnosis of Pneumocystis pneumonia was made based on a positive β-D-glucan assay and polymerase chain reaction amplification of Pneumocystis jirovecii from the sputum. Posttreatment FDG PET revealed resolution of the previously noted uptake. This case illustrates that FDG PET can be used to diagnose Pneumocystis pneumonia when the CT findings are equivocal.

Combustion of bulk titanium in oxygen

NASA Technical Reports Server (NTRS)

Clark, A. F.; Moulder, J. C.; Runyan, C. C.

1975-01-01

The combustion of bulk titanium in one atmosphere oxygen is studied using laser ignition and several analytical techniques. These were high-speed color cinematography, time and space resolved spectra in the visible region, metallography (including SEM) of specimens quenched in argon gas, X-ray and chemical product analyses, and a new optical technique, the Hilbert transform method. The cinematographic application of this technique for visualizing phase objects in the combustion zone is described. The results indicate an initial vapor phase reaction immediately adjacent to the molten surface but as the oxygen uptake progresses the evaporation approaches the point of congruency and a much reduced evaporation rate. This and the accumulation of the various soluble oxides soon drive the reaction zone below the surface where gas formation causes boiling and ejection of particles. The buildup of rutile cuts off the oxygen supply and the reaction ceases.

Effect of Toe Clips During Bicycle Ergometry on VO2 max.

ERIC Educational Resources Information Center

Moffat, Roger S.; Sparling, Phillip B.

1985-01-01

Eight men participated in three randomized maximal oxygen uptake tests to investigate the hypothesis that the use of toe clips on bicycle ergometers produced a higher VO2 max. No significant difference in mean VO2 max or performance time was observed. (Author/MT)

Higher Precision of Heart Rate Compared with VO2 to Predict Exercise Intensity in Endurance-Trained Runners.

PubMed

Reis, Victor M; den Tillaar, Roland Van; Marques, Mario C

2011-01-01

The aim of the present study was to assess the precision of oxygen uptake with heart rate regression during track running in highly-trained runners. Twelve national and international level male long-distance road runners (age 30.7 ± 5.5 yrs, height 1.71 ± 0.04 m and mass 61.2 ± 5.8 kg) with a personal best on the half marathon of 62 min 37 s ± 1 min 22 s participated in the study. Each participant performed, in an all-weather synthetic track five, six min bouts at constant velocity with each bout at an increased running velocity. The starting velocity was 3.33 m·s(-1) with a 0.56 m·s(-1) increase on each subsequent bout. VO2 and heart rate were measured during the runs and blood lactate was assessed immediately after each run. Mean peak VO2 and mean peak heart rate were, respectively, 76.2 ± 9.7 mL·kg(-1)·min(-1) and 181 ± 13 beats·min(-1). The linearity of the regressions between heart rate, running velocity and VO2 were all very high (r > 0.99) with small standard errors of regression (i.e. Sy.x < 5% at the velocity associated with the 2 and 4 mmol·L(-1) lactate thresholds). The strong relationships between heart rate, running velocity and VO2 found in this study show that, in highly trained runners, it is possible to have heart rate as an accurate indicator of energy demand and of the running speed. Therefore, in this subject cohort it may be unnecessary to use VO2 to track changes in the subjects' running economy during training periods. Key pointsHeart rate is used in the control of exercise intensity in endurance sports.However, few studies have quantified the precision of its relationship with oxygen uptake in highly trained runners.We evaluated twelve elite half-marathon runners during track running at various intensities and established three regressions: oxygen uptake / heart rate; heart rate / running velocity and oxygen uptake / running velocity.The three regressions presented, respectively, imprecision of 4,2%, 2,75% and 4,5% at the velocity associated with the 4 mmol·L(-1) threshold.The results of the present study show that, in highly trained runners, it is possible to use heart rate as an accurate index of the external work rate during sub maximal running speeds.

The Path of Carbon in Photosynthesis IX. Photosynthesis, Photoreduction, and the Hydrogen-Oxygen-Carbon Dioxide Dark Reaction

DOE R&D Accomplishments Database

Badin, E. J.; Calvin, M.

1950-02-01

A comparison of the rates of fixation of Carbon 14 dioxide in algae for the processes of photosynthesis, photoreduction and the hydrogen-oxygen-carbon dioxide dark reaction has been made. For the same series of experiments, rates of incorporation of tracer carbon into the separate soluble components using the radiogram method have been determined. The mechanism of carbon dioxide uptake has been shown to occur via two distinct paths. In all cases studied, essentially the same compounds appear radioactive. The distribution with time, however, differs markedly.

The Physiological Capacity of the World’s Highest Ranked Female Cross-country Skiers

PubMed Central

SANDBAKK, ØYVIND; HEGGE, ANN MAGDALEN; LOSNEGARD, THOMAS; SKATTEBO, ØYVIND; TØNNESSEN, ESPEN; HOLMBERG, HANS-CHRISTER

2016-01-01

ABSTRACT Purpose The objective of this study is to compare the physiological capacity and training characteristics of the world’s six highest ranked female cross-country skiers (world class (WC)) with those of six competitors of national class (NC). Methods Immediately before the start of the competition season, all skiers performed three 5-min submaximal stages of roller skiing on a treadmill for measurement of oxygen cost, as well as a 3-min self-paced performance test using both the double poling (DP) and diagonal stride (DIA) techniques. During the 3-min performance tests, the total distance covered, peak oxygen uptake (V˙O2peak), and accumulated oxygen deficit were determined. Each skier documented the intensity and mode of their training during the preceding 6 months in a diary. Results There were no differences between the groups with respect to oxygen cost or gross efficiency at the submaximal speeds. The WC skiers covered 6%–7% longer distances during the 3-min tests and exhibited average V˙O2peak values of ∼70 and ∼65 mL·min−1·kg−1 with DIA and DP, respectively, which were 10% and 7% higher than the NC skiers (all P < 0.05). However, the accumulated oxygen deficit did not differ between groups. From May to October, the WC skiers trained a total of 532 ± 73 h (270 ± 26 sessions) versus 411 ± 62 h (240 ± 27 sessions) for the NC skiers. In addition, the WC skiers performed 26% more low-intensity and almost twice as much moderate-intensity endurance and speed training (all P < 0.05). Conclusions This study highlights the importance of a high oxygen uptake and the ability to use this while performing the different skiing techniques on varying terrains for female cross-country skiers to win international races. In addition, the training data documented here provide benchmark values for female endurance athletes aiming for medals. PMID:26741124

CFD Study of Full-Scale Aerobic Bioreactors: Evaluation of Dynamic O2 Distribution, Gas-Liquid Mass Transfer and Reaction

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

Humbird, David; Sitaraman, Hariswaran; Stickel, Jonathan

If advanced biofuels are to measurably displace fossil fuels in the near term, they will have to operate at levels of scale, efficiency, and margin unprecedented in the current biotech industry. For aerobically-grown products in particular, scale-up is complex and the practical size, cost, and operability of extremely large reactors is not well understood. Put simply, the problem of how to attain fuel-class production scales comes down to cost-effective delivery of oxygen at high mass transfer rates and low capital and operating costs. To that end, very large reactor vessels (>500 m3) are proposed in order to achieve favorable economiesmore » of scale. Additionally, techno-economic evaluation indicates that bubble-column reactors are more cost-effective than stirred-tank reactors in many low-viscosity cultures. In order to advance the design of extremely large aerobic bioreactors, we have performed computational fluid dynamics (CFD) simulations of bubble-column reactors. A multiphase Euler-Euler model is used to explicitly account for the spatial distribution of air (i.e., gas bubbles) in the reactor. Expanding on the existing bioreactor CFD literature (typically focused on the hydrodynamics of bubbly flows), our simulations include interphase mass transfer of oxygen and a simple phenomenological reaction representing the uptake and consumption of dissolved oxygen by submerged cells. The simulations reproduce the expected flow profiles, with net upward flow in the center of column and downward flow near the wall. At high simulated oxygen uptake rates (OUR), oxygen-depleted regions can be observed in the reactor. By increasing the gas flow to enhance mixing and eliminate depleted areas, a maximum oxygen transfer (OTR) rate is obtained as a function of superficial velocity. These insights regarding minimum superficial velocity and maximum reactor size are incorporated into NREL's larger techno-economic models to supplement standard reactor design equations.« less

Electrical stimulation of human lower extremities enhances energy consumption, carbohydrate oxidation, and whole body glucose uptake.

PubMed

Hamada, Taku; Hayashi, Tatsuya; Kimura, Tetsuya; Nakao, Kazuwa; Moritani, Toshio

2004-03-01

Our laboratory has recently demonstrated that low-frequency electrical stimulation (ES) of quadriceps muscles alone significantly enhanced glucose disposal rate (GDR) during euglycemic clamp (Hamada T, Sasaki H, Hayashi T, Moritani T, and Nakao K. J Appl Physiol 94: 2107-2112, 2003). The present study is further follow-up to examine the acute metabolic effects of ES to lower extremities compared with voluntary cycle exercise (VE) at identical intensity. In eight male subjects lying in the supine position, both lower leg (tibialis anterior and triceps surae) and thigh (quadriceps and hamstrings) muscles were sequentially stimulated to cocontract in an isometric manner at 20 Hz with a 1-s on-off duty cycle for 20 min. Despite small elevation of oxygen uptake by 7.3 +/- 0.3 ml x kg(-1) x min(-1) during ES, the blood lactate concentration was significantly increased by 3.2 +/- 0.3 mmol/l in initial period (5 min) after the onset of the ES (P < 0.01), whereas VE showed no such changes at identical oxygen uptake (7.5 +/- 0.3 ml x kg(-1) x min(-1)). ES also induced enhanced whole body carbohydrate oxidation as shown by the significantly higher respiratory gas exchange ratio than with VE (P < 0.01). These data indicated increased anaerobic glycolysis by ES. Furthermore, whole body glucose uptake determined by GDR during euglycemic clamp demonstrated a significant increase during and after the cessation of ES for at least 90 min (P < 0.01). This post-ES effect was significantly greater than that of the post-VE period (P < 0.01). These results suggest that ES can substantially enhance energy consumption, carbohydrate oxidation, and whole body glucose uptake at low intensity of exercise. Percutaneous ES may become a therapeutic utility to enhance glucose metabolism in humans.

Response of benthic foraminifera to phytodetritus in the eastern Arabian Sea under low oxygen conditions

NASA Astrophysics Data System (ADS)

Enge, Annekatrin; Wukovits, Julia; Wanek, Wolfgang; Watzka, Margarete; Witte, Ursula; Hunter, William; Heinz, Petra

2016-04-01

At water depths between 100 and 1500 m a permanent Oxygen Minimum Zone (OMZ) impinges on the sea floor in the eastern Arabian Sea, exposing benthic organisms to anoxic to suboxic conditions. The flux of organic matter to the sea floor is relatively high at these depths but displays seasonal variation. Deposition of relatively fresh phytodetrital material (phytoplankton remains) can occur within a short period of time after monsoon periods. Several organism groups including foraminifera are involved to different extent in the processing of phytodetritus in the OMZs of the northern Arabian Sea. A series of in situ feeding experiments were performed to study the short-term processing (< 11 days) of organic carbon, nitrogen and nutritional demands of foraminifera at different oxygen concentrations on the continental margin in the eastern Arabian Sea. For the experiments, a single pulse of isotopically labeled phytodetritus was added to the sediment along a depth transect (540-1100 m) on the Indian Margin, covering the OMZ core and the lower OMZ boundary region. Uptake of phytodetritus within 4 days shows the relevance of phytodetritus as food source for foraminifera. Lower content of phytodetrital carbon recorded in foraminifera from more oxygenated depths shows greater food uptake by foraminifera in the OMZ core than in the OMZ boundary region. The foraminiferal assemblage living under almost anoxic conditions in the OMZ core is dominated by species typically found in eutroph environments (such as Uvigerinids) that are adapted to high flux of organic matter. The elevated carbon uptake can also result from missing food competition by macrofauna or from greater energy demand in foraminifera to sustain metabolic processes under hypoxic stress. Variable levels and ratios of phytodetrital carbon and nitrogen indicate specific nutritional demands and storage of food-derived nitrogen in some foraminifera species under near anoxia where the mean phytodetrital nitrogen content in foraminifera was elevated. In summary, foraminifera dominate the short-term processing of phytodetritus by fauna in the OMZ core but are less important in the lower OMZ boundary region of the Indian margin as a result of biological interactions and changes in the distribution of individual foraminiferal species.

Uptake of algal carbon and the synthesis of an "essential" fatty acid by Uvigerina ex. gr. semiornata (Foraminifera) within the Pakistan margin oxygen minimum zone: evidence from fatty acid biomarker and 13C tracer experiments

NASA Astrophysics Data System (ADS)

Larkin, K. E.; Gooday, A. J.; Woulds, C.; Jeffreys, R.; Schwartz, M.; Cowie, G.; Whitcraft, C.; Levin, L.; Dick, J. R.; Pond, D. W.

2014-01-01

Foraminifera are an important component of benthic communities in oxygen depleted settings, where they potentially play a~significant role in the processing of organic matter. We tracked the uptake of a 13C-labeled algal food source into individual fatty acids in the benthic foraminiferal species, Uvigerina ex. gr. semiornata, from the Arabian Sea oxygen minimum zone (OMZ). The tracer experiments were conducted on the Pakistan Margin during the late/post monsoon period (August-October 2003). A monoculture of the diatom Thalassiosira weisflogii was 13C-labeled and used to simulate a pulse of phytoplankton in two complementary experiments. A lander system was used for in situ incubations at 140 m and for 2.5 days duration, whilst a laboratory incubation used an oxystat system to maintain ambient dissolved oxygen concentrations. These shipboard experiments were terminated after 5 days. Uptake of diatoms was rapid, with high incorporation of diatom fatty acids into foraminifera after ~2 days in both experiments. Ingestion of the diatom food source was indicated by the increase over time in the quantity of diatom biomarker fatty acids in the foraminifera and by the high percentage of 13C in many of the fatty acids present at the endpoint of both in~situ and laboratory-based experiments. These results indicate that U. ex. gr. semiornata rapidly ingested the diatom food source and that this foraminifera will play an important role in the short-term cycling of organic matter within this OMZ environment. The experiments also suggested that U. ex. gr. semiornata consumed non-labeled bacterial food items, particularly bacteria, and synthesised the polyunsaturated fatty acid 20:4(n-6) de novo. 20:4(n-6) is often abundant in benthic fauna yet its origins and function have remained unclear. This study demonstrates that U. ex. gr. semiornata is capable of de novo synthesis of this "essential fatty acid" and is potentially a major source of this dietary nutrient in benthic food webs.

Reflectance spectroscopy can quantify cutaneous haemoglobin oxygenation by oxygen uptake from the atmosphere after epidermal barrier disruption.

PubMed

Heise, H M; Lampen, P; Stücker, M

2003-11-01

The supply of oxygen to the viable skin tissue within the upper layers is not only secured by the cutaneous blood vascular system, but to a significant part also by oxygen diffusion from the atmosphere through the horny layer. The aim of this study was to examine whether changes in haemoglobin oxygenation can be observed within the isolated perfused bovine udder skin used as a skin model by removing the upper horny layer by adhesive tape stripping. Diffuse reflectance spectroscopy in the visible spectral range was used for non-invasive characterisation of haemoglobin oxygenation in skin under in vitro conditions. Mid-infrared attenuated total reflectance spectroscopy was employed for analysing the surface layer of the stratum corneum with respect to keratin, water and lipid components. Skin barrier disruption was achieved by repeated stripping of superficial corneocyte layers by adhesive tape. Significant changes in skin haemoglobin oxygenation were observed for skin areas with reduced lipid concentration and a reduced stratum corneum layer, as determined from the quantitative evaluation of the diffuse reflectance skin spectra. The result can be interpreted as an increase of oxygen diffusion after the removal of the upper horny layer.

Energy metabolism and glutamate-glutamine cycle in the brain: a stoichiometric modeling perspective.

PubMed

Massucci, Francesco A; DiNuzzo, Mauro; Giove, Federico; Maraviglia, Bruno; Castillo, Isaac Perez; Marinari, Enzo; De Martino, Andrea

2013-10-10

The energetics of cerebral activity critically relies on the functional and metabolic interactions between neurons and astrocytes. Important open questions include the relation between neuronal versus astrocytic energy demand, glucose uptake and intercellular lactate transfer, as well as their dependence on the level of activity. We have developed a large-scale, constraint-based network model of the metabolic partnership between astrocytes and glutamatergic neurons that allows for a quantitative appraisal of the extent to which stoichiometry alone drives the energetics of the system. We find that the velocity of the glutamate-glutamine cycle (Vcyc) explains part of the uncoupling between glucose and oxygen utilization at increasing Vcyc levels. Thus, we are able to characterize different activation states in terms of the tissue oxygen-glucose index (OGI). Calculations show that glucose is taken up and metabolized according to cellular energy requirements, and that partitioning of the sugar between different cell types is not significantly affected by Vcyc. Furthermore, both the direction and magnitude of the lactate shuttle between neurons and astrocytes turn out to depend on the relative cell glucose uptake while being roughly independent of Vcyc. These findings suggest that, in absence of ad hoc activity-related constraints on neuronal and astrocytic metabolism, the glutamate-glutamine cycle does not control the relative energy demand of neurons and astrocytes, and hence their glucose uptake and lactate exchange.

Energy metabolism and glutamate-glutamine cycle in the brain: a stoichiometric modeling perspective

PubMed Central

2013-01-01

Background The energetics of cerebral activity critically relies on the functional and metabolic interactions between neurons and astrocytes. Important open questions include the relation between neuronal versus astrocytic energy demand, glucose uptake and intercellular lactate transfer, as well as their dependence on the level of activity. Results We have developed a large-scale, constraint-based network model of the metabolic partnership between astrocytes and glutamatergic neurons that allows for a quantitative appraisal of the extent to which stoichiometry alone drives the energetics of the system. We find that the velocity of the glutamate-glutamine cycle (Vcyc) explains part of the uncoupling between glucose and oxygen utilization at increasing Vcyc levels. Thus, we are able to characterize different activation states in terms of the tissue oxygen-glucose index (OGI). Calculations show that glucose is taken up and metabolized according to cellular energy requirements, and that partitioning of the sugar between different cell types is not significantly affected by Vcyc. Furthermore, both the direction and magnitude of the lactate shuttle between neurons and astrocytes turn out to depend on the relative cell glucose uptake while being roughly independent of Vcyc. Conclusions These findings suggest that, in absence of ad hoc activity-related constraints on neuronal and astrocytic metabolism, the glutamate-glutamine cycle does not control the relative energy demand of neurons and astrocytes, and hence their glucose uptake and lactate exchange. PMID:24112710

The Net Physiological Cost of Dribbling a Soccer Ball.

ERIC Educational Resources Information Center

Reilly, Thomas; Ball, David

1984-01-01

To establish the net energy cost of dribbling a soccer ball, eight males ran on a treadmill while dribbling a ball against a rebound box. Oxygen uptake, perceived exertion, and blood lactate levels were measured and compared with results from subjects running without dribbling. Results are discussed. (Author/DF)

Williams during the PFE-OUM Experiment in the US Lab during Expedition 15

NASA Image and Video Library

2007-05-24

ISS015-E-09461 (24 May 2007) --- Astronaut Sunita L. Williams, Expedition 15 flight engineer, exercises on the Cycle Ergometer with Vibration Isolation System (CEVIS) during a Periodic Fitness Evaluation with Oxygen Uptake Measurement (PFE-OUM) experiment in the Destiny laboratory of the International Space Station.

Inhibitory effect of cyanide on wastewater nitrification determined using SOUR and RNA-based gene-specific assays

EPA Science Inventory

The effect of CN- (CN-) on nitrification was examined with samples from nitrifying wastewater enrichments using two different approaches: by measuring substrate (ammonia) specific oxygen uptake rates (SOUR), and by using RT-qPCR to quantify the transcripts of functional genes inv...

Body Composition and Aerobic Requirements of Male and Female Marathon Runners.

ERIC Educational Resources Information Center

Wells, Christine L.; And Others

This study investigates the physical characteristics, body composition, cardiovascular and pulmonary functions, and aerobic capabilities of male and female long distance runners. Eleven runners volunteered to take tests to determine background information, body fat, oxygen uptake, and running time and pace. Conclusions made from this study…

A Physiologic Profile Comparing Levels and Styles of Female Dancers.

ERIC Educational Resources Information Center

Chmelar, Robin D.; And Others

1988-01-01

Comparison of 39 adult female dancers indicated that professional ballet dancers had significantly lower maximal oxygen uptake and lower peak blood lactate levels than other dancers (professional modern, university ballet or modern). Professional ballet dancers also had a significantly higher isokinetic hamstring-quadriceps ratio than modern…

Psychological and Metabolic Correlates of Obesity in African-Americans and Caucasians

DTIC Science & Technology

2006-01-01

29% fat, and 14.6% protein. Ensure was available in vanilla, chocolate, strawberry, and butter pecan . This liquid meal has been used previously in...oxygen uptake, carbon dioxide production, and respiratory exchange ratio by open circuit spirometry (KB20-CosMed, Italy ). Maximal exercise test

Research report on: Specialized physiological studies in support of manned space flight

NASA Technical Reports Server (NTRS)

Luft, U. C.

1975-01-01

An investigation of the role of 02 fluctuations in oxygen uptake observed with changing posture is reported. A comparison of the closing volume test with other pulmonary function measurements is presented along with a comparison of hydrostatic weighing, and a stereophotogrammetric method for determining body volume.

40 CFR 503.33 - Vector attraction reduction.

Code of Federal Regulations, 2013 CFR

2013-07-01

... less than 15 percent, vector attraction reduction is achieved. (4) The specific oxygen uptake rate... shall be equal to or greater than 75 percent based on the moisture content and total solids prior to... the moisture content and total solids prior to mixing with other materials. (9)(i) Sewage sludge shall...

40 CFR 503.33 - Vector attraction reduction.

Code of Federal Regulations, 2014 CFR

2014-07-01

... less than 15 percent, vector attraction reduction is achieved. (4) The specific oxygen uptake rate... shall be equal to or greater than 75 percent based on the moisture content and total solids prior to... the moisture content and total solids prior to mixing with other materials. (9)(i) Sewage sludge shall...

40 CFR 503.33 - Vector attraction reduction.

Code of Federal Regulations, 2010 CFR

2010-07-01

... less than 15 percent, vector attraction reduction is achieved. (4) The specific oxygen uptake rate... shall be equal to or greater than 75 percent based on the moisture content and total solids prior to... the moisture content and total solids prior to mixing with other materials. (9)(i) Sewage sludge shall...

40 CFR 503.33 - Vector attraction reduction.

Code of Federal Regulations, 2011 CFR

2011-07-01

... less than 15 percent, vector attraction reduction is achieved. (4) The specific oxygen uptake rate... shall be equal to or greater than 75 percent based on the moisture content and total solids prior to... the moisture content and total solids prior to mixing with other materials. (9)(i) Sewage sludge shall...

40 CFR 503.33 - Vector attraction reduction.

Code of Federal Regulations, 2012 CFR

2012-07-01

... less than 15 percent, vector attraction reduction is achieved. (4) The specific oxygen uptake rate... shall be equal to or greater than 75 percent based on the moisture content and total solids prior to... the moisture content and total solids prior to mixing with other materials. (9)(i) Sewage sludge shall...

Effect of abomasal butyrate infusion on gene expression in the duodenum of lambs

USDA-ARS?s Scientific Manuscript database

A previous study infusing butyrate into the abomasum of sheep produced increased oxygen, glucose, glutamate, and glutamine uptake by the portal-drained viscera. These changes were thought to be partially due to increases in glycolysis and cell proliferation. The purpose of this study was to evaluate...

Skeletal muscle protein accretion rates and hindlimb growth are reduced in late gestation intrauterine growth-restricted fetal sheep.

PubMed

Rozance, Paul J; Zastoupil, Laura; Wesolowski, Stephanie R; Goldstrohm, David A; Strahan, Brittany; Cree-Green, Melanie; Sheffield-Moore, Melinda; Meschia, Giacomo; Hay, William W; Wilkening, Randall B; Brown, Laura D

2018-01-01

Adults who were affected by intrauterine growth restriction (IUGR) suffer from reductions in muscle mass, which may contribute to insulin resistance and the development of diabetes. We demonstrate slower hindlimb linear growth and muscle protein synthesis rates that match the reduced hindlimb blood flow and oxygen consumption rates in IUGR fetal sheep. These adaptations resulted in hindlimb blood flow rates in IUGR that were similar to control fetuses on a weight-specific basis. Net hindlimb glucose uptake and lactate output rates were similar between groups, whereas amino acid uptake was significantly lower in IUGR fetal sheep. Among all fetuses, blood O 2 saturation and plasma glucose, insulin and insulin-like growth factor-1 were positively associated and norepinephrine was negatively associated with hindlimb weight. These results further our understanding of the metabolic and hormonal adaptations to reduced oxygen and nutrient supply with placental insufficiency that develop to slow hindlimb growth and muscle protein accretion. Reduced skeletal muscle mass in the fetus with intrauterine growth restriction (IUGR) persists into adulthood and may contribute to increased metabolic disease risk. To determine how placental insufficiency with reduced oxygen and nutrient supply to the fetus affects hindlimb blood flow, substrate uptake and protein accretion rates in skeletal muscle, late gestation control (CON) (n = 8) and IUGR (n = 13) fetal sheep were catheterized with aortic and femoral catheters and a flow transducer around the external iliac artery. Muscle protein kinetic rates were measured using isotopic tracers. Hindlimb weight, linear growth rate, muscle protein accretion rate and fractional synthetic rate were lower in IUGR compared to CON (P < 0.05). Absolute hindlimb blood flow was reduced in IUGR (IUGR: 32.9 ± 5.6 ml min -1 ; CON: 60.9 ± 6.5 ml min -1 ; P < 0.005), although flow normalized to hindlimb weight was similar between groups. Hindlimb oxygen consumption rate was lower in IUGR (IUGR: 10.4 ± 1.4 μmol min -1  100 g -1 ; CON: 14.7 ± 1.3 μmol min -1  100 g -1 ; P < 0.05). Hindlimb glucose uptake and lactate output rates were similar between groups, whereas amino acid uptake was lower in IUGR (IUGR: 1.3 ± 0.5 μmol min -1  100 g -1 ; CON: 2.9 ± 0.2 μmol min -1  100 g -1 ; P < 0.05). Blood O 2 saturation (r 2  = 0.80, P < 0.0001) and plasma glucose (r 2  = 0.68, P < 0.0001), insulin (r 2  = 0.40, P < 0.005) and insulin-like growth factor (IGF)-1 (r 2  = 0.80, P < 0.0001) were positively associated and norepinephrine (r 2  = 0.59, P < 0.0001) was negatively associated with hindlimb weight. Slower hindlimb linear growth and muscle protein synthesis rates match reduced hindlimb blood flow and oxygen consumption rates in the IUGR fetus. Metabolic adaptations to slow hindlimb growth are probably hormonally-mediated by mechanisms that include increased fetal norepinephrine and reduced IGF-1 and insulin. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

Residence time control on hot moments of net nitrate production and uptake in the hyporheic zone

USGS Publications Warehouse

Briggs, Martin A.; Lautz, Laura K.; Hare, Danielle K.

2014-01-01

moments of net production and uptake, enhancing NO3- production as residence times approach the anaerobic threshold, and changing zones of net NO3- production to uptake as residence times increase past the net sink threshold. The anaerobic and net sink thresholds for beaver-influenced streambed morphology occur at much shorter residence times (1.3 h and 2.3 h, respectively) compared to other documented hyporheic systems, and the net sink threshold compares favorably to the lower boundary of the anaerobic threshold determined for this system with the new oxygen Damkohler number. The consistency of the residence time threshold values of NO3- cycling in this study, despite environmental variability and disparate morphology, indicates that NO3- hot moment dynamics are primarily driven by changes in physical hydrology and associated residence times.

Fe-S cluster biosynthesis controls uptake of aminoglycosides in a ROS-less death pathway.

PubMed

Ezraty, Benjamin; Vergnes, Alexandra; Banzhaf, Manuel; Duverger, Yohann; Huguenot, Allison; Brochado, Ana Rita; Su, Shu-Yi; Espinosa, Leon; Loiseau, Laurent; Py, Béatrice; Typas, Athanasios; Barras, Frédéric

2013-06-28

All bactericidal antibiotics were recently proposed to kill by inducing reactive oxygen species (ROS) production, causing destabilization of iron-sulfur (Fe-S) clusters and generating Fenton chemistry. We find that the ROS response is dispensable upon treatment with bactericidal antibiotics. Furthermore, we demonstrate that Fe-S clusters are required for killing only by aminoglycosides. In contrast to cells, using the major Fe-S cluster biosynthesis machinery, ISC, cells using the alternative machinery, SUF, cannot efficiently mature respiratory complexes I and II, resulting in impendence of the proton motive force (PMF), which is required for bactericidal aminoglycoside uptake. Similarly, during iron limitation, cells become intrinsically resistant to aminoglycosides by switching from ISC to SUF and down-regulating both respiratory complexes. We conclude that Fe-S proteins promote aminoglycoside killing by enabling their uptake.

Lack of appropriate stoichiometry: Strong evidence against an energetically important astrocyte-neuron lactate shuttle in brain.

PubMed

Dienel, Gerald A

2017-11-01

Glutamate-stimulated aerobic glycolysis in astrocytes coupled with lactate shuttling to neurons where it can be oxidized was proposed as a mechanism to couple excitatory neuronal activity with glucose utilization (CMR glc ) during brain activation. From the outset, this model was not viable because it did not fulfill critical stoichiometric requirements: (i) Calculated glycolytic rates and measured lactate release rates were discordant in cultured astrocytes. (ii) Lactate oxidation requires oxygen consumption, but the oxygen-glucose index (OGI, calculated as CMR O2 /CMR glc ) fell during activation in human brain, and the small rise in CMR O2 could not fully support oxidation of lactate produced by disproportionate increases in CMR glc . (iii) Labeled products of glucose metabolism are not retained in activated rat brain, indicating rapid release of a highly labeled, diffusible metabolite identified as lactate, thereby explaining the CMR glc -CMR O2 mismatch. Additional independent lines of evidence against lactate shuttling include the following: astrocytic oxidation of glutamate after its uptake can help "pay" for its uptake without stimulating glycolysis; blockade of glutamate receptors during activation in vivo prevents upregulation of metabolism and lactate release without impairing glutamate uptake; blockade of β-adrenergic receptors prevents the fall in OGI in activated human and rat brain while allowing glutamate uptake; and neurons upregulate glucose utilization in vivo and in vitro under many stimulatory conditions. Studies in immature cultured cells are not appropriate models for lactate shuttling in adult brain because of their incomplete development of metabolic capability and astrocyte-neuron interactions. Astrocyte-neuron lactate shuttling does not make large, metabolically significant contributions to energetics of brain activation. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

A modelling approach for the heterogeneous oxidation of elastomers

NASA Astrophysics Data System (ADS)

Herzig, A.; Sekerakova, L.; Johlitz, M.; Lion, A.

2017-09-01

The influence of oxygen on elastomers, known as oxidation, is one of the most important ageing processes and becomes more and more important for nowadays applications. The interaction with thermal effects as well as antioxidants makes oxidation of polymers a complex process. Based on the polymer chosen and environmental conditions, the ageing processes may behave completely different. In a lot of cases the influence of oxygen is limited to the surface layer of the samples, commonly referred to as diffusion-limited oxidation. For the lifetime prediction of elastomer components, it is essential to have detailed knowledge about the absorption and diffusion behaviour of oxygen molecules during thermo-oxidative ageing and how they react with the elastomer. Experimental investigations on industrially used elastomeric materials are executed in order to develop and fit models, which shall be capable of predicting the permeation and consumption of oxygen as well as changes in the mechanical properties. The latter are of prime importance for technical applications of rubber components. Oxidation does not occur homogeneously over the entire elastomeric component. Hence, material models which include ageing effects have to be amplified in order to consider heterogeneous ageing, which highly depends on the ageing temperature. The influence of elevated temperatures upon accelerated ageing has to be critically analysed, and influences on the permeation and diffusion coefficient have to be taken into account. This work presents phenomenological models which describe the oxygen uptake and the diffusion into elastomers based on an improved understanding of ongoing chemical processes and diffusion limiting modifications. On the one side, oxygen uptake is modelled by means of Henry's law in which solubility is a function of the temperature as well as the ageing progress. The latter is an irreversible process and described by an inner differential evolution equation. On the other side, further diffusion of oxygen into the material is described by a model based on Fick's law, which is modified by a reaction term. The evolved diffusion-reaction equation depends on the ageing temperature as well as on the progress of ageing and is able to describe diffusion-limited oxidation.

Effect of free fatty acids on myocardial function and metabolism in the ischemic dog heart

PubMed Central

Kjekshus, John K.; Mjøs, Ole D.

1972-01-01

Since elevation of plasma concentrations of free fatty acids (FFA) increases myocardial oxygen consumption without influencing mechanical performance in normal hearts, it was the purpose of this study to determine whether FFA would modify mechanical performance at limited oxygen supply. Left coronary blood flow was reduced by gradual clamping of a shunt from the left carotid artery until moderate ventricular dilatation supervened. Left ventricular systolic pressure (LVSP), its maximal rate of rise (dP/dt) and stroke volume (SV) were unchanged or slightly reduced. The ischemia resulted in a decrease in myocardial oxygen consumption (MVO2) from 9.7±1.1 ml/min to 7.9±0.8 ml/min, and myocardial lactate uptake was reduced or reversed to excretion. Increasing the plasma concentrations of FFA from 359±47 μEq/1 to 3688±520 μEq/1 by intravenous infusion of a triglyceride emulsion and heparin resulted in further ventricular dilatation, accompanied by increased excretion of lactate. The ventricular decompensation and enhancement of anaerobic myocardial metabolism associated with increased uptake of FFA was not related to changes in coronary flow, MVO2, or LVSP. dP/dt and SV were virtually unchanged. Intravenous infusion of glucose/insulin, which lowered plasma concentrations of FFA, reversed ventricular dilatation and lactate excretion. The data support the hypothesis that high concentrations of FFA play a significant role in increasing myocardial oxygen requirement and thereby promote depression of contractility of the hypoxic heart in experimental animals. Images PMID:5032525

Validation of a dual-cycle ergometer for exercise during 100 percent oxygen prebreathing

NASA Technical Reports Server (NTRS)

Wiegman, Janet F.; Ohlhausen, John H.; Webb, James T.; Pilmanis, Andrew A.

1992-01-01

A study has been designed to determine if exercise, while prebreathing 100 percent oxygen prior to decompression, can reduce the current resting-prebreathe time requirements for extravehicular activity and high altitude reconnaissance flight. For that study, a suitable exercise mode was required. Design considerations included space limitations, cost, pressure suit compatibility, ease and maintenance of calibration, accuracy of work output, and assurance that no significant mechanical advantage or disadvantage would be introduced into the system. In addition, the exercise device must enhance denitrogenation by incorporation of both upper and lower body musculature at high levels of oxygen consumption. The purpose of this paper is to describe the specially constructed, dual-cycle ergometer developed for simultaneous arm and leg exercise during prebreathing, and to compare maximal oxygen uptake obtained on the device to that obtained during leg-only cycle ergometry and treadmill testing. Results demonstrate the suitability of the dual-cycle ergometer as an appropriate tool for exercise research during 100 percent oxygen prebreathing.

[Oxygen consumption in the lungs and systemic circulation--different methods of measurement of one data or different data?].

PubMed

Perfilova, A V; Gromova, T A; Lebedinskiĭ, K M; Zaĭchik, A M

2014-01-01

The article deals with calculation of oxygen consumption in the lungs by means of breathing gas mixture analysis and in parallel--in the systemic circulation by reverse Fick method; 32 paired measurements were performed in 8 patients after cardiac surgery with cardiopulmonary bypass. The mean pulmonary oxygen consumption was higher than the same value calculated by the reverse Fick principle--148.4 +/- 39.9 ml x min(-1) x m(-2) and 120 +/- 35.1 ml x min(-1) x m(-2), respectively, the mean difference between two methods was 28.4 +/- 18.4 ml x min(-1) x m(-2). However, in two observations the interrelation was inversed. While analyzing physiological and methodological reasons for these differences, the authors concluded that, despite both methods can be used in monitoring systemic oxygen transport in the critically ill, they are not interchangeable, and valuable additional data could be derived from fast changes in lungs oxygen uptake.

Inferring foliar water uptake using stable isotopes of water.

PubMed

Goldsmith, Gregory R; Lehmann, Marco M; Cernusak, Lucas A; Arend, Matthias; Siegwolf, Rolf T W

2017-08-01

A growing number of studies have described the direct absorption of water into leaves, a phenomenon known as foliar water uptake. The resultant increase in the amount of water in the leaf can be important for plant function. Exposing leaves to isotopically enriched or depleted water sources has become a common method for establishing whether or not a plant is capable of carrying out foliar water uptake. However, a careful inspection of our understanding of the fluxes of water isotopes between leaves and the atmosphere under high humidity conditions shows that there can clearly be isotopic exchange between the two pools even in the absence of a change in the mass of water in the leaf. We provide experimental evidence that while leaf water isotope ratios may change following exposure to a fog event using water with a depleted oxygen isotope ratio, leaf mass only changes when leaves are experiencing a water deficit that creates a driving gradient for the uptake of water by the leaf. Studies that rely on stable isotopes of water as a means of studying plant water use, particularly with respect to foliar water uptake, must consider the effects of these isotopic exchange processes.

All About Oxygen in the Ocean: Cheap, Quick and Easy Experiments for Pupils Grades 5 to 10

NASA Astrophysics Data System (ADS)

Soria-Dengg, S.

2015-12-01

The collaborative research project (SFB 754) at GEOMAR Helmholtz-Centre for Ocean Research Kiel, Germany addresses among others the decreasing concentrations of oxygen in the oceans. The school outreach component of the SFB 754 a project funded by the German Science Foundation aims to spread the science behind ocean de-oxygenation in secondary schools in Germany. To realise this goal, a series of hands-on experiments have been developed on different topics like gas solubility in water, gas transport in the ocean, oxygen production by phytoplankton, oxygen consumption by bacteria and experiments on nutrient uptake by phytoplankton. The experiments developed are simple, using low cost and reusable materials thus ensuring affordability in schools. For the hands-on session the following experiments will be presented: (1) The effects of temperature, oxygen partial pressure, nature of solute and nature of solvent on the solubility of oxygen in water will be demonstrated using Luer-Lock syringes, (2) Oxygen transport from the ocean surface to the deep will be shown in an experiment using a modification of the "blue-bottle" experiment, and (3) Simulation of ocean circulation employing a 2-dimensional tank. Applications and experiment ideas using immobilised phytoplankton and other procedures suitable for schools for measuring oxygen consumption by bacteria will be introduced in a poster presentation.

The effect of acute temperature increases on the cardiorespiratory performance of resting and swimming sockeye salmon (Oncorhynchus nerka).

PubMed

Steinhausen, M F; Sandblom, E; Eliason, E J; Verhille, C; Farrell, A P

2008-12-01

The mechanism underlying the decrease in aerobic scope in fish at warm temperatures is not fully understood and is the focus of this research. Our study examined oxygen uptake and delivery in resting, swimming and recovering sockeye salmon while water temperature was acutely increased from 15 degrees C to 24 degrees C in 2 degrees C h(-1) increments. Fish swam at a constant speed during the temperature change. By simultaneously measuring oxygen consumption (M(O(2))), cardiac output (Q) and the blood oxygen status of arterial and venous blood, we were able to determine where in the oxygen cascade a limitation appeared when fish stopped sustained swimming as temperature increased. High temperature fatigue of swimming sockeye salmon was not a result of a failure of either oxygen delivery to the gills or oxygen diffusion at the gills because oxygen partial pressure (P(O(2))) and oxygen content (C(O(2))) in arterial blood did not decrease with increasing temperature, as would be predicted for such limitations. Instead, arterial oxygen delivery (Ta(O(2))) was initially hampered due to a failure to adequately increase Q with increasing temperature. Subsequently, lactate appeared in the blood and venous P(O(2)) remained constant.

Evaluating the Efficacy of GLUT Inhibitors Using a Seahorse Extracellular Flux Analyzer.

PubMed

Wei, Changyong; Heitmeier, Monique; Hruz, Paul W; Shanmugam, Mala

2018-01-01

Glucose is metabolized through anaerobic glycolysis and aerobic oxidative phosphorylation (OXPHOS). Perturbing glucose uptake and its subsequent metabolism can alter both glycolytic and OXPHOS pathways and consequently lactate and/or oxygen consumption. Production and secretion of lactate, as a consequence of glycolysis, leads to acidification of the extracellular medium. Molecular oxygen is the final electron acceptor in the electron transport chain, facilitating oxidative phosphorylation of ADP to ATP. The alterations in extracellular acidification and/or oxygen consumption can thus be used as indirect readouts of glucose metabolism and assessing the impact of inhibiting glucose transport through specific glucose transporters (GLUTs). The Seahorse bioenergetics analyzer can measure both the oxygen consumption rate (OCR) and extracellular acidification rate (ECAR). The proposed methodology affords a robust, high-throughput method to screen for GLUT inhibition in cells engineered to express specific GLUTs, providing live cell read-outs upon GLUT inhibition.

Methylene Blue Protects Astrocytes against Glucose Oxygen Deprivation by Improving Cellular Respiration

PubMed Central

Roy Choudhury, Gourav; Winters, Ali; Rich, Ryan M.; Ryou, Myoung-Gwi; Gryczynski, Zygmunt; Yuan, Fang; Yang, Shao-Hua; Liu, Ran

2015-01-01

Astrocytes outnumber neurons and serve many metabolic and trophic functions in the mammalian brain. Preserving astrocytes is critical for normal brain function as well as for protecting the brain against various insults. Our previous studies have indicated that methylene blue (MB) functions as an alternative electron carrier and enhances brain metabolism. In addition, MB has been shown to be protective against neurodegeneration and brain injury. In the current study, we investigated the protective role of MB in astrocytes. Cell viability assays showed that MB treatment significantly protected primary astrocytes from oxygen-glucose deprivation (OGD) & reoxygenation induced cell death. We also studied the effect of MB on cellular oxygen and glucose metabolism in primary astrocytes following OGD-reoxygenation injury. MB treatment significantly increased cellular oxygen consumption, glucose uptake and ATP production in primary astrocytes. In conclusion our study demonstrated that MB protects astrocytes against OGD-reoxygenation injury by improving astrocyte cellular respiration. PMID:25848957

Biodegradation of halothane, enflurane and methoxyflurane.

PubMed

Sakai, T; Takaori, M

1978-08-01

The biodegradation of halothane, enflurane and methoxyflurane was studied in 22 patients undergoing abdominal surgery, by measuring the uptake and elimination of each agent and the fluoride excretion in urine. Six control patients were anaesthetized with nitrous oxide in oxygen together with neuromuscular blocking drugs, five patients with nitrous oxide in oxygen and 0.93% halothane, five with nitrous oxide in oxygen and 1.30% enflurane, and six with nitrous oxide in oxygen and 0.31% methoxyflurane. The ratio of the fluoride excretion in urine to the total amount of fluoride contained in the amount of each anaesthetic agent absorbed during anaesthesia was estimated to be 17.7% for halothane, 2.3% for enflurane and 46.3% for methoxyflurane. The serum fluoride concentration increased to a maximum of 15.8 +/- 3.8 mumol litre-1 (mean +/- SD) at 6 h after anaesthesia with methoxyflurane, while it did not exceed 8 mumol litre-1 with the other anaesthetic agents.

[Exercise-related risk at anaerobic threshold in patients with chronic obstructive pulmonary disease].

PubMed

Xu, Q F; Yuan, W; Zhao, X J; Li, B; Wang, H Y

2016-02-01

To investigate the exercise-related risk at anaerobic threshold(AT) in patients with chronic obstructive pulmonary disease(COPD). Sixty two patients [men 56, women 6, aged (66±8) yr] with stable COPD in Beijing Friendship Hospital during 2013-2014, participated in this study. Incremental symptom-limited cardiopulmonary exercise test was performed on cycle ergometer. The AT was determined using the V-Slope technique and ventilatory equivalents for carbon dioxide and oxygen. Symptoms, 10-lead electrocardiogram, oxygen saturation by pulse oximetry(SpO(2)) were monitored during exercise. The AT, detectable in 53 patients, occurred at (68±10)% of peak oxygen uptake(peak VO(2)). The SpO(2) was in the safe range (94±2) % and the respiratory reserve was relatively high at AT (i.e. 48%). High-intensity exercise training can be performed in patients with moderate-to- severe COPD without resting oxygen desaturation.

Energetics of osmoregulation: I. Oxygen consumption by Fundulus heteroclitus.

PubMed

Kidder, George W; Petersen, Christopher W; Preston, Robert L

2006-04-01

We have developed a flow-through method for measuring oxygen consumption in fish which allows continuous monitoring over periods of days with good accuracy. Our goal was to determine the changes in basal metabolic rate in estuarine fish as a function of salinity. We show that in Fundulus heteroclitus, the oxygen consumption drops by 50% during the first 12 hr in the respirometer, as the fish cease exploratory movements. We have determined the influence of temperature and body size on resting respiratory rate, but failed to find any circadian or tidal rhythm in aerobic respiration. With these variables controlled, we determined that changing from 10 to 30 ppt water had no demonstrable effect on oxygen uptake. Since there must be a large change in osmotic flux due to this change in salinity, it appears that the fish might be diverting energy from other uses rather than increasing aerobic energy production to meet the increased osmoregulatory work load.

Influence of dissolved oxygen concentration on the pharmacokinetics of alcohol in humans.

PubMed

Baek, In-hwan; Lee, Byung-yo; Kwon, Kwang-il

2010-05-01

Ethanol oxidation by the microsomal ethanol oxidizing system requires oxygen for alcohol metabolism, and a higher oxygen uptake increases the rate of ethanol oxidation. We investigated the effect of dissolved oxygen on the pharmacokinetics of alcohol in healthy humans (n = 49). The concentrations of dissolved oxygen were 8, 20, and 25 ppm in alcoholic drinks of 240 and 360 ml (19.5% v/v). Blood alcohol concentrations (BACs) were determined by converting breath alcohol concentrations. Breath samples were collected every 30 min when the BAC was higher than 0.015%, 20 min at BAC < or =0.015%, 10 min at BAC < or =0.010%, and 5 min at BAC < or =0.006%. The high dissolved oxygen groups (20, 25 ppm) descended to 0.000% and 0.050% BAC faster than the normal dissolved oxygen groups (8 ppm; p < 0.05). In analyzing pharmacokinetic parameters, AUC(inf) and K(el) of the high oxygen groups were lower than in the normal oxygen group, while C(max) and T(max) were not significantly affected. In a Monte Carlo simulation, the lognormal distribution of mean values of AUC(inf) and t(1/2) was expected to be reduced in the high oxygen group compared to the normal oxygen group. In conclusion, elevated dissolved oxygen concentrations in alcoholic drinks accelerate the metabolism and elimination of alcohol. Thus, enhanced dissolved oxygen concentrations in alcohol may have a role to play in reducing alcohol-related side effects and accidents.

Receptor-Mediated Uptake of Phosphorothioate Antisense Oligonucleotides in Different Cell Types of the Liver.

PubMed

Miller, Colton M; Tanowitz, Michael; Donner, Aaron J; Prakash, Thazha P; Swayze, Eric E; Harris, Edward N; Seth, Punit P

2018-06-01

Oligonucleotide therapeutics have emerged as a third distinct platform for drug discovery within the pharmaceutical industry. Five oligonucleotide-based drugs have been approved by the US FDA and over 100 oligonucleotides drugs are currently at different stages of human trials. Several of these oligonucleotide drugs are modified using the phosphorothioate (PS) backbone modification where one of the nonbridging oxygen atoms of the phosphodiester linkage is replaced with sulfur. In this review, we summarize our knowledge on receptor-mediated uptake of PS antisense oligonucleotides (ASOs) within different cell types of the liver-a privileged organ for the discovery of oligonucleotide-based therapeutics.

Critical evaluation of oxygen-uptake assessment in swimming.

PubMed

Sousa, Ana; Figueiredo, Pedro; Pendergast, David; Kjendlie, Per-Ludvik; Vilas-Boas, João P; Fernandes, Ricardo J

2014-03-01

Swimming has become an important area of sport science research since the 1970s, with the bioenergetic factors assuming a fundamental performance-influencing role. The purpose of this study was to conduct a critical evaluation of the literature concerning oxygen-uptake (VO2) assessment in swimming, by describing the equipment and methods used and emphasizing the recent works conducted in ecological conditions. Particularly in swimming, due to the inherent technical constraints imposed by swimming in a water environment, assessment of VO2max was not accomplished until the 1960s. Later, the development of automated portable measurement devices allowed VO2max to be assessed more easily, even in ecological swimming conditions, but few studies have been conducted in swimming-pool conditions with portable breath-by-breath telemetric systems. An inverse relationship exists between the velocity corresponding to VO2max and the time a swimmer can sustain it at this velocity. The energy cost of swimming varies according to its association with velocity variability. As, in the end, the supply of oxygen (whose limitation may be due to central-O2 delivery and transportation to the working muscles-or peripheral factors-O2 diffusion and utilization in the muscles) is one of the critical factors that determine swimming performance, VO2 kinetics and its maximal values are critical in understanding swimmers' behavior in competition and to develop efficient training programs.

Steap4 Plays a Critical Role in Osteoclastogenesis in Vitro by Regulating Cellular Iron/Reactive Oxygen Species (ROS) Levels and cAMP Response Element-binding Protein (CREB) Activation*

PubMed Central

Zhou, Jian; Ye, Shiqiao; Fujiwara, Toshifumi; Manolagas, Stavros C.; Zhao, Haibo

2013-01-01

Iron is essential for osteoclast differentiation, and iron overload in a variety of hematologic diseases is associated with excessive bone resorption. Iron uptake by osteoclast precursors via the transferrin cycle increases mitochondrial biogenesis, reactive oxygen species production, and activation of cAMP response element-binding protein, a critical transcription factor downstream of receptor activator of NF-κB-ligand-induced calcium signaling. These changes are required for the differentiation of osteoclast precursors to mature bone-resorbing osteoclasts. However, the molecular mechanisms regulating cellular iron metabolism in osteoclasts remain largely unknown. In this report, we provide evidence that Steap4, a member of the six-transmembrane epithelial antigen of prostate (Steap) family proteins, is an endosomal ferrireductase with a critical role in cellular iron utilization in osteoclasts. Specifically, we show that Steap4 is the only Steap family protein that is up-regulated during osteoclast differentiation. Knocking down Steap4 expression in vitro by lentivirus-mediated short hairpin RNAs inhibits osteoclast formation and decreases cellular ferrous iron, reactive oxygen species, and the activation of cAMP response element-binding protein. These results demonstrate that Steap4 is a critical enzyme for cellular iron uptake and utilization in osteoclasts and, thus, indispensable for osteoclast development and function. PMID:23990467

Bacterial and chemical oxidation of pyritic mine tailings at low temperatures

NASA Astrophysics Data System (ADS)

Elberling, Bo; Schippers, Axel; Sand, Wolfgang

2000-02-01

Microbial and chemical sulfide oxidation activity and oxygen consumption was investigated in the active layer of pyritic mine tailings at Nanisivik Mine, located in a permafrost area on Baffin Island in northern Canada. Samples of tailings were collected up to a depth of 60 cm in mid-August 1998 at 4 sites, for which the metabolic activity of sulfur- and iron-oxidizing leaching bacteria besides the chemical pyrite oxidation activity were measured on 39 tailings samples and 7 samples from a natural pyritic site by calorimetry. The tailings of varying age and water content were deposited under alkaline conditions. In situ oxygen uptake rates were measured at the tailings surface every third day, prior to sampling. In addition, cell counts of iron(II), sulfur, and thiosulfate oxidizing, lithotrophic bacteria and chemoorganotrophic microorganisms were determined quantitatively by the most-probable-number technique or by agar-plating. Results show consistent pyrite oxidation rates based on in situ oxygen uptake rates, and laboratory heat output measurements. Litho- and organotrophic bacteria were found in the tailings. Calorimetric measurements revealed that the present bacterial activity is responsible for approximately one third of the ongoing oxidation. Although leaching bacteria have previously been found in the Arctic, this study is the first to prove the significance of bacterial activity in the overall pollution resulting from tailings deposited in the Arctic.

Energy system contribution in a maximal incremental test: correlations with pacing and overall performance in a 10-km running trial.

PubMed

Damasceno, M V; Pasqua, L A; Lima-Silva, A E; Bertuzzi, R

2015-11-01

This study aimed to verify the association between the contribution of energy systems during an incremental exercise test (IET), pacing, and performance during a 10-km running time trial. Thirteen male recreational runners completed an incremental exercise test on a treadmill to determine the respiratory compensation point (RCP), maximal oxygen uptake (V˙O2max), peak treadmill speed (PTS), and energy systems contribution; and a 10-km running time trial (T10-km) to determine endurance performance. The fractions of the aerobic (WAER) and glycolytic (WGLYCOL) contributions were calculated for each stage based on the oxygen uptake and the oxygen energy equivalents derived by blood lactate accumulation, respectively. Total metabolic demand (WTOTAL) was the sum of these two energy systems. Endurance performance during the T10-km was moderately correlated with RCP, V˙O2max and PTS (P<@0.05), and moderate-to-highly correlated with WAER, WGLYCOL, and WTOTAL (P<0.05). In addition, WAER, WGLYCOL, and WTOTAL were also significantly correlated with running speed in the middle (P<0.01) and final (P<0.01) sections of the T10-km. These findings suggest that the assessment of energy contribution during IET is potentially useful as an alternative variable in the evaluation of endurance runners, especially because of its relationship with specific parts of a long-distance race.

Morning-to-evening differences in oxygen uptake kinetics in short-duration cycling exercise.

PubMed

Brisswalter, Jeanick; Bieuzen, François; Giacomoni, Magali; Tricot, Véronique; Falgairette, Guy

2007-01-01

This study analyzed diurnal variations in oxygen (O(2)) uptake kinetics and efficiency during a moderate cycle ergometer exercise. Fourteen physically active diurnally active male subjects (age 23+/-5 yrs) not specifically trained at cycling first completed a test to determine their ventilatory threshold (T(vent)) and maximal oxygen consumption (VO(2max)); one week later, they completed four bouts of testing in the morning and evening in a random order, each separated by at least 24 h. For each period of the day (07:00-08:30 h and 19:00-20:30 h), subjects performed two bouts. Each bout was composed of a 5 min cycling exercise at 45 W, followed after 5 min rest by a 10 min cycling exercise at 80% of the power output associated with T(vent). Gas exchanges were analyzed breath-by-breath and fitted using a mono-exponential function. During moderate exercise, the time constant and amplitude of VO(2) kinetics were significantly higher in the morning compared to the evening. The net efficiency increased from the morning to evening (17.3+/-4 vs. 20.5+/-2%; p<0.05), and the variability of cycling cadence was greater during the morning than evening (+34%; p<0.05). These findings suggest that VO(2) responses are affected by the time of day and could be related to variability in muscle activity pattern.

Metabolic cost of over ground gait in younger stroke patients and healthy controls.

PubMed

Platts, Marina M; Rafferty, Daniel; Paul, Lorna

2006-06-01

Locomotor impairment, such as that which may occur following a stroke, results in increased energy expenditure during walking. Previous research quantifying this increased metabolic demand has focused on older people; thus, the aim of this study was to investigate the physiological cost of walking in younger patients following stroke. Thirteen stroke patients (mean age of 40.7+/-10.0 yr) and 13 age- and sex-matched controls participated. Each subject walked for 5 min around an elliptical course (two cones set 9.5 m apart) at their own preferred walking speed (PWS). The percentage of expired oxygen was measured using a portable gas analyzer. Following a 5-min rest, the control subjects repeated the procedure, but at the PWS of the patient to whom they were matched. The PWS of the stroke patients was significantly lower than that of the controls (P<0.001); however, there was no significant difference in terms of oxygen uptake (P=0.403). When the distance walked was considered, there was a statistically significant difference in oxygen uptake per unit of distance between the two groups (P<0.001) and also between the patients PWS and the controls walking at the PWS of the patients. The high metabolic cost of walking would suggest that, even for younger stroke patients, early rehabilitation should consider aerobic evaluation and training with the aim of optimizing functional independence.

Perceptions of hyperbaric oxygen therapy among podiatrists practicing in high-risk foot clinics.

PubMed

Henshaw, Frances R; Brennan, Lauren; MacMillan, Freya

2018-01-03

Foot ulceration is a devastating and costly consequence of diabetes. Hyperbaric oxygen therapy is recognised as an adjunctive therapy to treat diabetes-related foot ulceration, yet uptake is low. Semi-structured interviews were conducted with 16 podiatrists who manage patients with foot ulcers related to diabetes to explore their perceptions of, and the barriers/facilitators to, referral for hyperbaric oxygen. Podiatrists cited logistical issues such as location of facilities as well as poor communication pathways, lack of delegation and lack of follow up when patients presented for hyperbaric treatment. In general, podiatrists had an understanding of the premise of hyperbaric oxygen therapy and evidence to support its use but could only provide very limited citations of key papers and guidelines to support their position. Podiatrists stated that they felt a patient was lost from their care when referred for hyperbaric oxygen and that aftercare might not be adequate. Improved referral and delegation pathways for patients presenting for hyperbaric oxygen, as well as the provision of easily accessible evidence to support this therapy, could help to increase podiatrists' confidence in deciding whether or not to recommend their patients for hyperbaric oxygen therapy. © 2018 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

Adaptation to Aerobic Environment of Lactobacillus johnsonii/gasseri Strains

PubMed Central

Maresca, Diamante; Zotta, Teresa; Mauriello, Gianluigi

2018-01-01

Oxygen is considered one of the main factors affecting probiotic bacteria survival due to the induction of oxidative damages caused by the action of reactive oxygen species (ROS). It has been shown that oxidative stress resistance in lactic acid bacteria is strongly dependent on the type of cell metabolism. Shift from fermentative to respiratory metabolism (through the addition of heme and menaquinone and in presence of oxygen) was associated to increase in biomass, long-term survival, and production of antioxidant enzymes. The aim of this work was to investigate the effect of aerobic (presence of oxygen) and respiratory (presence of oxygen, heme, and menaquinone) cultivation on the growth kinetic, catalase production, oxygen uptake, and oxidative stress response of Lactobacillus johnsonii/gasseri strains previously isolated from infant feces. Seven strains showed to consume oxygen under aerobic and respiratory conditions. The strain AL5 showed a catalase activity in both growth conditions, while AL3 showed this activity only in respiratory condition. Respiratory condition improved their tolerance to oxidative compounds (hydrogen peroxide and ROS generators) and further they showed promising probiotic features. The exploration of respiratory competent phenotypes with probiotic features may be extremely useful for the development of competitive starter or probiotic cultures. PMID:29479342

Adaptation to Aerobic Environment of Lactobacillus johnsonii/gasseri Strains.

PubMed

Maresca, Diamante; Zotta, Teresa; Mauriello, Gianluigi

2018-01-01

Oxygen is considered one of the main factors affecting probiotic bacteria survival due to the induction of oxidative damages caused by the action of reactive oxygen species (ROS). It has been shown that oxidative stress resistance in lactic acid bacteria is strongly dependent on the type of cell metabolism. Shift from fermentative to respiratory metabolism (through the addition of heme and menaquinone and in presence of oxygen) was associated to increase in biomass, long-term survival, and production of antioxidant enzymes. The aim of this work was to investigate the effect of aerobic (presence of oxygen) and respiratory (presence of oxygen, heme, and menaquinone) cultivation on the growth kinetic, catalase production, oxygen uptake, and oxidative stress response of Lactobacillus johnsonii/gasseri strains previously isolated from infant feces. Seven strains showed to consume oxygen under aerobic and respiratory conditions. The strain AL5 showed a catalase activity in both growth conditions, while AL3 showed this activity only in respiratory condition. Respiratory condition improved their tolerance to oxidative compounds (hydrogen peroxide and ROS generators) and further they showed promising probiotic features. The exploration of respiratory competent phenotypes with probiotic features may be extremely useful for the development of competitive starter or probiotic cultures.

Pharmacological and gene regulation properties point to the SlHAK5 K+ transporter as a system for high-affinity Cs+ uptake in tomato plants.

PubMed

Ródenas, Reyes; Nieves-Cordones, Manuel; Rivero, Rosa M; Martinez, Vicente; Rubio, Francisco

2018-04-01

Potassium (K + ) and cesium (Cs + ) are chemically similar but while K + is an essential nutrient, Cs + can be toxic for living organisms, plants included. Two different situations could lead to problems derived from the presence of Cs + in agricultural systems: (1) presence of Cs + at high concentrations that could produce toxic effects on plants, (2) presence of micromolar concentrations of radiocesium, which can be accumulated in the plant and affect animal and human health through the food chain. While K + uptake has been well described in tomato plants, information on molecular mechanisms involved in Cs + accumulation in this species is absent. Here, we show that in tomato plants, high concentrations of Cs + produce deficiency of K + but do not induce high-affinity K + uptake or the gene encoding the high-affinity K + transporter SlHAK5. At these concentrations, Cs + uptake takes place through a Ca 2+ -sensitive pathway, probably a non-selective cation channel. At micromolar concentrations, Cs + is accumulated by a high-affinity uptake system upregulated in K + -starved plants. This high-affinity Cs + uptake shares features with high-affinity K + uptake. It is sensitive to NH 4 + and insensitive to Ba 2+ and Ca 2+ and its presence parallels the pattern of SlHAK5 expression. Moreover, blockers of reactive oxygen species and ethylene action repress SlHAK5 and negatively regulate both high-affinity K + and Cs + uptake. Thus, we propose that SlHAK5 contributes to Cs + uptake from micromolar concentrations in tomato plants and can constitute a pathway for radiocesium transfer from contaminated areas to the food chain. © 2017 Scandinavian Plant Physiology Society.

Effect of Caffeine Ingestion on Cardiorespiratory Endurance in Men and Women.

ERIC Educational Resources Information Center

Butts, N. K.; Crowell, D.

1985-01-01

Oxygen uptake, heart rate, and rating of perceived exertion were used to measure the effect of caffeine ingestion on active college students. The results do not support the general use of caffeine as an ergogenic aid for either males or females, although caffeine may have that effect on specific individuals. (Author/MT)

Influence of biochar pyrolysis temperature and post-treatment on the uptake of mercury from flue gas

USDA-ARS?s Scientific Manuscript database

Thermal processing, or pyrolysis, of plant and animal waste under oxygen limiting conditions results in a carbonized material called biochar. Most often, the proposed application for the biochar is soil applications as a conditioner or for the purpose of carbon sequestration. In this paper we demons...

Determining Intensity Levels of Selected Wii Fit Activities in College Aged Individuals

ERIC Educational Resources Information Center

Grieser, Joshua D.; Gao, Yong; Ransdell, Lynda; Simonson, Shawn

2012-01-01

The purpose of this study was to determine the intensity of Nintendo Wii Fit games using indirect calorimetry. Twenty-five college students completed Wii Fit activity sessions at two difficulty levels within aerobics, strength, and yoga categories. Resting metabolic rate and exercise oxygen uptake were measured, and metabolic equivalents were…

Variability of Respiration and Metabolism: Responses to Submaximal Cycling and Running.

ERIC Educational Resources Information Center

Armstrong, Lawrence E.; Costill, David L.

1985-01-01

This investigation examined day-to-day variations in metabolic measurements during submaximal running and cycling. Significant differences were found in the oxygen uptake (VO2) of runners and cyclists and the minute ventilation (VE) of cyclists while running, but blood lactic acid (HLA) did not differ day to day. (Author/MT)

Monitoring wheat mitochondrial compositional and respiratory changes using Fourier transform mid-infrared spectroscopy in response to agrochemical treatments

USDA-ARS?s Scientific Manuscript database

Fungicides and plant growth regulators can impact plant growth outside of their effects on fungal pathogens. Although many of these chemicals are inhibitors of mitochondrial oxygen uptake, information remains limited as to whether they are able tomodify other mitochondrial constituents. Fourier tran...

Effect of heavy metals on nitrification activity as measured by RNA- and DNA-based function-specific assays

EPA Science Inventory

Heavy metals can inhibit nitrification, a key process for nitrogen removal in wastewater treatment. The transcriptional responses of functional genes (amoA, hao, nirK and norB) were measured in conjunction with specific oxygen uptake rate (sOUR) for nitrifying enrichment cultures...

Aerosol optical hygroscopicity measurements during the 2010 CARES Campaign

NASA Astrophysics Data System (ADS)

Atkinson, D. B.; Radney, J. G.; Lum, J.; Kolesar, K. R.; Cziczo, D. J.; Pekour, M. S.; Zhang, Q.; Setyan, A.; Zelenyuk, A.; Cappa, C. D.

2014-12-01

Measurements of the effect of water uptake on particulate light extinction or scattering made at two locations during the 2010 CARES study around Sacramento, CA are reported. The observed influence of water uptake, characterized through the dimensionless optical hygroscopicity parameter γ, is compared with calculations constrained by observed particle size distributions and size-dependent particle composition. A closure assessment has been carried out that allowed for determination of the average hygroscopic growth factors (GF) at 85% relative humidity and the dimensionless hygroscopicity parameter κ for oxygenated organic aerosol (OA) and for supermicron particles, yielding κ = 0.1-0.15 and 0.9-1.0, respectively. The derived range of oxygenated OA κ values are in line with previous observations. The relatively large values for supermicron particles is consistent with substantial contributions of sea salt-containing particles in this size range. Analysis of time-dependent variations in the supermicron particle hygroscopicity suggest that atmospheric processing, specifically chloride displacement by nitrate and the accumulation of secondary organics on supermicron particles, can lead to substantial depression of the observed GF.

Respirometric response and microbial succession of nitrifying sludge to m-cresol pulses in a sequencing batch reactor.

PubMed

Ordaz, Alberto; Sánchez, Mariana; Rivera, Rodrigo; Rojas, Rafael; Zepeda, Alejandro

2017-02-01

A nitrifying consortium was kinetically, stoichiometrically and molecularly characterized via the in situ pulse respirometric method and pyrosequencing analysis before and after the addition of m-cresol (25 mg C L -1 ) in a sequencing batch reactor (SBR). Five important kinetic and stoichiometric parameters were determined: the maximum oxygen uptake rate, the maximum nitrification rate, the oxidation yield, the biomass growth yield, and the substrate affinity constant. An inhibitory effect was observed in the nitrification process with a recovery of this by up to eight SBR cycles after m-cresol was added to the system. However, full recovery of the nitrification process was not observed, as the maximum oxygen uptake rate was 25% lower than that of the previous operation without m-cresol addition. Furthermore, the pyrosequencing analyses of the nitrifying consortium after the addition of only two pulses of 25 mg C L -1 m-cresol showed an important microbial community change represented by a decrease in the nitrifying populations and an increase in the populations degrading phenolic compounds.

The relationships between fish health, metabolic rate, swimming performance and recovery in return-run sockeye salmon, Oncorhynchus nerka (Walbaum).

PubMed

Tierney, K B; Farrell, A P

2004-11-01

The repeat swimming ability and oxygen uptake (Mo2) of adult sockeye salmon, Oncorhynchus nerka (Walbaum), were assessed at ambient water temperatures at three field locations along their migration route. Following these measurements, internal and external fish condition was evaluated according to United States Environmental Protection Agency guidelines. Here we report on the physiological characteristics of fish having either moderate or severe levels of disease and injury. Routine oxygen uptake (Mo2) did not differ between healthy fish and those with indices of ill health. In contrast, fish classified as sick, which included conditions of damaged internal organs, an Ichthyophonus spp. heart infection, a Saprolegnia spp. gill infection, and skin wounds, had a lower post-exercise Mo2 and were unable to repeat their critical swim speed (U(crit)) on the second swim test. Moderate levels of disease or injury did not significantly affect either U(crit) or post-exercise Mo2. We conclude that the ability of adult salmon to recover quickly from exercise may be a useful indicator of sublethal pathologies.

Sugar-mediated acclimation: the importance of sucrose metabolism in meristems.

PubMed

Carpentier, Sebastien Christian; Vertommen, Annelies; Swennen, Rony; Witters, Erwin; Fortes, Claudia; Souza, Manoel T; Panis, Bart

2010-10-01

We have designed an in vitro experimental setup to study the role of sucrose in sugar-mediated acclimation of banana meristems using established highly proliferating meristem cultures. It is a first step toward the systems biology of a meristem and the understanding of how it can survive severe abiotic stress. Using the 2D-DIGE proteomic approach and a meristem-specific EST library, we describe the long-term acclimation response of banana meristems (after 2, 4, 8, and 14 days) and analyze the role of sucrose in this acclimation by setting up a control, a sorbitol, and a sucrose acclimation treatment over time. Sucrose synthase is the dominant enzyme for sucrose breakdown in meristem tissue, which is most likely related to its lower energy consumption. Metabolizing sucrose is of paramount importance to survive, but the uptake of sugar and its metabolism also drive respiration, which may result in limited oxygen levels. According to our data, a successful acclimation is correlated to an initial efficient uptake of sucrose and subsequently a reduced breakdown of sucrose and an induction of fermentation likely by a lack of oxygen.

Brazilian Twin Registry: A Bright Future for Twin Studies/Twin Research: Twin Study of Alcohol Consumption and Mortality; Oxygen Uptake in Adolescent Twins/In the News: Superfecundated Twins In Vietnam; Adolescent Twin Relations; Twin and Triplet Co-Workers; A Special Twin Ultrasound; Monozygotic Twins With Different Skin Color; Identical Twin Returns from Space.

PubMed

Segal, Nancy L

2016-06-01

The establishment of the Brazilian Twin Registry for the study of genetic, social, and cultural influences on behavior is one of eleven newly funded projects in the Department of Psychology at the University of São Paulo. These 11 interrelated projects form the core of the university's Center for Applied Research on Well-Being and Human Behavior. An overview of the planned twin research and activities to date is presented. Next, two recent twin studies are reviewed, one on the relationship between alcohol consumption and mortality, and the other on factors affecting maximal oxygen uptake. Twins cited in the media include the first identified superfecundated twins in Vietnam, adolescent twin relations, twins and triplets who work together, monozygotic twins with different skin tones and a co-twin control study that addresses the effects of space travel.

Modified Active Videogame Play Results in Moderate-Intensity Exercise.

PubMed

Monedero, Javier; McDonnell, Adam C; Keoghan, Melissa; O'Gorman, Donal J

2014-08-01

Large proportions of the population do not meet current American College of Sports Medicine physical activity recommendations, and innovative approaches are required. Most active videogames do not require a significant amount of energy expenditure. The purpose of this study was to determine if modifying an active videogame increased exercise intensity to meet current physical activity recommendations. After completing a maximal oxygen uptake test, participants did a familiarization session on a separate day. Thirteen healthy participants 24.2±3.4 years of age played (1) a sedentary videogame, (2) an active videogame, and (3) a modified active videogame designed to increase physical activity for 46 minutes in a randomized order on separate days. Oxygen uptake, heart rate, heart rate reserve, percentage of maximal heart rate, metabolic equivalents of task, and energy expenditure were significantly higher during the modified active videogame trial than during the active videogame or sedentary videogame trials and also between the active videogame and sedentary videogame. A simple modification to an existing active videogame was sufficient to reach moderate exercise intensity. Active videogames could provide an important option for increasing daily physical activity and reducing sedentary time.

Stress, workload and physiology demand during extravehicular activity: a pilot study.

PubMed

Rai, Balwant; Kaur, Jasdeep; Foing, Bernard H

2012-06-01

Extravehicular activity (EVA), such as exercise performed under unique environmental conditions, is essential for supporting daily living in weightlessness and for further space exploration like long Mars mission. The study was planned stress, workload, and physiological demands of simulated Mars exploration. In this study, the six-person crew lived (24 hours) for 14 days during a short-term stay at the Mars Desert Research Station. The heart rates, salivary cortisol, workload, peak oxygen uptake or maximal aerobic capacity of the crew are measured before, during and after an EVA. Data for heart rate showed the same trend as peak oxygen uptake or maximal aerobic capacity, with a maximal increase to 85% of peak. The rating of subscale showed a significant increase in EVA as compared to run. Salivary cortisol levels and heart rates were increased in both groups, although significant increased of cortisol levels and heart rates more in EVA as compared to hill running crew members. Further study is required on large scale taken into account of limitations of this study and including other physiological and psychological parameters in Mars analog environment.

Spirolit-2 instrument used to test pulmonary ventilation

NASA Astrophysics Data System (ADS)

Zhuravlev, V. V.

1985-02-01

At the present time, the Spirolit-2 automatic analyzer of main respiratory gases, of the Junkalor Dessau firm, is used to examine parameters of gas exchange, levels of energy expended by man and animals with different degrees of activity. However, the capabilities of this model of the instrument are limited. A method of determining pulmonary ventilation with use of the Spirolit-2 is described. An additional exhalation valve is built into a valve box to which an anesthesia machine rubber bag is attached. Samples are collected into another bag concurrently with the usual tests on the Spirolit-2 instrument. Four to five minutes are sufficient to obtain stable parameters at relative rest of oxygen uptake, determine carbon dioxide output per minute and collect samples in for analysis of exhaled air. The proposed method can furnish information about the dynamics of development of respiratory function of the lungs at virtually any moment with a constant physical load. For this, there must be spare bags to collect samples. Stage-by-stage data can be obtained analogously as to ventilation volume during a step test while determining maximum oxygen uptake.

Depth of soil water uptake by tropical rainforest trees during dry periods: does tree dimension matter?

PubMed

Stahl, Clément; Hérault, Bruno; Rossi, Vivien; Burban, Benoit; Bréchet, Claude; Bonal, Damien

2013-12-01

Though the root biomass of tropical rainforest trees is concentrated in the upper soil layers, soil water uptake by deep roots has been shown to contribute to tree transpiration. A precise evaluation of the relationship between tree dimensions and depth of water uptake would be useful in tree-based modelling approaches designed to anticipate the response of tropical rainforest ecosystems to future changes in environmental conditions. We used an innovative dual-isotope labelling approach (deuterium in surface soil and oxygen at 120-cm depth) coupled with a modelling approach to investigate the role of tree dimensions in soil water uptake in a tropical rainforest exposed to seasonal drought. We studied 65 trees of varying diameter and height and with a wide range of predawn leaf water potential (Ψpd) values. We confirmed that about half of the studied trees relied on soil water below 100-cm depth during dry periods. Ψpd was negatively correlated with depth of water extraction and can be taken as a rough proxy of this depth. Some trees showed considerable plasticity in their depth of water uptake, exhibiting an efficient adaptive strategy for water and nutrient resource acquisition. We did not find a strong relationship between tree dimensions and depth of water uptake. While tall trees preferentially extract water from layers below 100-cm depth, shorter trees show broad variations in mean depth of water uptake. This precludes the use of tree dimensions to parameterize functional models.

Implementing oxygen control in chip-based cell and tissue culture systems.

PubMed

Oomen, Pieter E; Skolimowski, Maciej D; Verpoorte, Elisabeth

2016-09-21

Oxygen is essential in the energy metabolism of cells, as well as being an important regulatory parameter influencing cell differentiation and function. Interest in precise oxygen control for in vitro cultures of tissues and cells continues to grow, especially with the emergence of the organ-on-a-chip and the desire to emulate in vivo conditions. This was recently discussed in this journal in a Critical Review by Brennan et al. (Lab Chip (2014). DOI: ). Microfluidics can be used to introduce flow to facilitate nutrient supply to and waste removal from in vitro culture systems. Well-defined oxygen gradients can also be established. However, cells can quickly alter the oxygen balance in their vicinity. In this Tutorial Review, we expand on the Brennan paper to focus on the implementation of oxygen analysis in these systems to achieve continuous monitoring. Both electrochemical and optical approaches for the integration of oxygen monitoring in microfluidic tissue and cell culture systems will be discussed. Differences in oxygen requirements from one organ to the next are a challenging problem, as oxygen delivery is limited by its uptake into medium. Hence, we discuss the factors determining oxygen concentrations in solutions and consider the possible use of artificial oxygen carriers to increase dissolved oxygen concentrations. The selection of device material for applications requiring precise oxygen control is discussed in detail, focusing on oxygen permeability. Lastly, a variety of devices is presented, showing the diversity of approaches that can be employed to control and monitor oxygen concentrations in in vitro experiments.

Extracellular Vesicles from Hypoxic Adipocytes and Obese Subjects Reduce Insulin‐Stimulated Glucose Uptake

PubMed Central

Mleczko, Justyna; Ortega, Francisco J.; Falcon‐Perez, Juan Manuel; Wabitsch, Martin; Fernandez‐Real, Jose Manuel

2018-01-01

Scope We investigate the effects of extracellular vesicles (EVs) obtained from in vitro adipocyte cell models and from obese subjects on glucose transport and insulin responsiveness. Methods and results EVs are isolated from the culture supernatant of adipocytes cultured under normoxia, hypoxia (1% oxygen), or exposed to macrophage conditioned media (15% v/v). EVs are isolated from the plasma of lean individuals and subjects with obesity. Cultured adipocytes are incubated with EVs and activation of insulin signalling cascades and insulin‐stimulated glucose transport are measured. EVs released from hypoxic adipocytes impair insulin‐stimulated 2‐deoxyglucose uptake and reduce insulin mediated phosphorylation of AKT. Insulin‐mediated phosphorylation of extracellular regulated kinases (ERK1/2) is not affected. EVs from individuals with obesity decrease insulin stimulated 2‐deoxyglucose uptake in adipocytes (p = 0.0159). Conclusion EVs released by stressed adipocytes impair insulin action in neighboring adipocytes. PMID:29292863

Oxygen Response of the Wine Yeast Saccharomyces cerevisiae EC1118 Grown under Carbon-Sufficient, Nitrogen-Limited Enological Conditions

PubMed Central

Aceituno, Felipe F.; Orellana, Marcelo; Torres, Jorge; Mendoza, Sebastián; Slater, Alex W.; Melo, Francisco

2012-01-01

Discrete additions of oxygen play a critical role in alcoholic fermentation. However, few studies have quantitated the fate of dissolved oxygen and its impact on wine yeast cell physiology under enological conditions. We simulated the range of dissolved oxygen concentrations that occur after a pump-over during the winemaking process by sparging nitrogen-limited continuous cultures with oxygen-nitrogen gaseous mixtures. When the dissolved oxygen concentration increased from 1.2 to 2.7 μM, yeast cells changed from a fully fermentative to a mixed respirofermentative metabolism. This transition is characterized by a switch in the operation of the tricarboxylic acid cycle (TCA) and an activation of NADH shuttling from the cytosol to mitochondria. Nevertheless, fermentative ethanol production remained the major cytosolic NADH sink under all oxygen conditions, suggesting that the limitation of mitochondrial NADH reoxidation is the major cause of the Crabtree effect. This is reinforced by the induction of several key respiratory genes by oxygen, despite the high sugar concentration, indicating that oxygen overrides glucose repression. Genes associated with other processes, such as proline uptake, cell wall remodeling, and oxidative stress, were also significantly affected by oxygen. The results of this study indicate that respiration is responsible for a substantial part of the oxygen response in yeast cells during alcoholic fermentation. This information will facilitate the development of temporal oxygen addition strategies to optimize yeast performance in industrial fermentations. PMID:23001663

Oxygen response of the wine yeast Saccharomyces cerevisiae EC1118 grown under carbon-sufficient, nitrogen-limited enological conditions.

PubMed

Aceituno, Felipe F; Orellana, Marcelo; Torres, Jorge; Mendoza, Sebastián; Slater, Alex W; Melo, Francisco; Agosin, Eduardo

2012-12-01

Discrete additions of oxygen play a critical role in alcoholic fermentation. However, few studies have quantitated the fate of dissolved oxygen and its impact on wine yeast cell physiology under enological conditions. We simulated the range of dissolved oxygen concentrations that occur after a pump-over during the winemaking process by sparging nitrogen-limited continuous cultures with oxygen-nitrogen gaseous mixtures. When the dissolved oxygen concentration increased from 1.2 to 2.7 μM, yeast cells changed from a fully fermentative to a mixed respirofermentative metabolism. This transition is characterized by a switch in the operation of the tricarboxylic acid cycle (TCA) and an activation of NADH shuttling from the cytosol to mitochondria. Nevertheless, fermentative ethanol production remained the major cytosolic NADH sink under all oxygen conditions, suggesting that the limitation of mitochondrial NADH reoxidation is the major cause of the Crabtree effect. This is reinforced by the induction of several key respiratory genes by oxygen, despite the high sugar concentration, indicating that oxygen overrides glucose repression. Genes associated with other processes, such as proline uptake, cell wall remodeling, and oxidative stress, were also significantly affected by oxygen. The results of this study indicate that respiration is responsible for a substantial part of the oxygen response in yeast cells during alcoholic fermentation. This information will facilitate the development of temporal oxygen addition strategies to optimize yeast performance in industrial fermentations.

3D modeling of effects of increased oxygenation and activity concentration in tumors treated with radionuclides and antiangiogenic drugs

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

Lagerloef, Jakob H.; Kindblom, Jon; Bernhardt, Peter

Purpose: Formation of new blood vessels (angiogenesis) in response to hypoxia is a fundamental event in the process of tumor growth and metastatic dissemination. However, abnormalities in tumor neovasculature often induce increased interstitial pressure (IP) and further reduce oxygenation (pO{sub 2}) of tumor cells. In radiotherapy, well-oxygenated tumors favor treatment. Antiangiogenic drugs may lower IP in the tumor, improving perfusion, pO{sub 2} and drug uptake, by reducing the number of malfunctioning vessels in the tissue. This study aims to create a model for quantifying the effects of altered pO{sub 2}-distribution due to antiangiogenic treatment in combination with radionuclide therapy. Methods:more » Based on experimental data, describing the effects of antiangiogenic agents on oxygenation of GlioblastomaMultiforme (GBM), a single cell based 3D model, including 10{sup 10} tumor cells, was developed, showing how radionuclide therapy response improves as tumor oxygenation approaches normal tissue levels. The nuclides studied were {sup 90}Y, {sup 131}I, {sup 177}Lu, and {sup 211}At. The absorbed dose levels required for a tumor control probability (TCP) of 0.990 are compared for three different log-normal pO{sub 2}-distributions: {mu}{sub 1} = 2.483, {sigma}{sub 1} = 0.711; {mu}{sub 2} = 2.946, {sigma}{sub 2} = 0.689; {mu}{sub 3} = 3.689, and {sigma}{sub 3} = 0.330. The normal tissue absorbed doses will, in turn, depend on this. These distributions were chosen to represent the expected oxygen levels in an untreated hypoxic tumor, a hypoxic tumor treated with an anti-VEGF agent, and in normal, fully-oxygenated tissue, respectively. The former two are fitted to experimental data. The geometric oxygen distributions are simulated using two different patterns: one Monte Carlo based and one radially increasing, while keeping the log-normal volumetric distributions intact. Oxygen and activity are distributed, according to the same pattern. Results: As tumor pO{sub 2} approaches normal tissue levels, the therapeutic effect is improved so that the normal tissue absorbed doses can be decreased by more than 95%, while retaining TCP, in the most favorable scenario and by up to about 80% with oxygen levels previously achieved in vivo, when the least favourable oxygenation case is used as starting point. The major difference occurs in poorly oxygenated cells. This is also where the pO{sub 2}-dependence of the oxygen enhancement ratio is maximal. Conclusions: Improved tumor oxygenation together with increased radionuclide uptake show great potential for optimising treatment strategies, leaving room for successive treatments, or lowering absorbed dose to normal tissues, due to increased tumor response. Further studies of the concomitant use of antiangiogenic drugs and radionuclide therapy therefore appear merited.« less

Size-related bioconcentration kinetics of hydrophobic chemicals in fish

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

Sijm, D.T.H.M.; Linde, A. van der

1994-12-31

Uptake and elimination of hydrophobic chemicals by fish can be regarded as passive diffusive transport processes. Diffusion coefficients, lipid/water partitioning, diffusion pathlenghts, concentration gradients and surface exchange areas are key parameters describing this bioconcentration distribution process. In the present study two of these parameters were studied: the influence of lipid/water partitioning was studied by using hydrophobic chemicals of different hydrophobicity, and the surface exchange area by using different sizes of fish. By using one species of fish it was assumed that all other parameters were kept constant. Seven age classes of fish were exposed to a series of hydrophobic, formore » five days, which was followed by a deputation phase lasting up to 6 months. Bioconcentration parameters, such as uptake and elimination rate constants, and bioconcentration factors were determined. Uptake of the hydrophobic compounds was compared to that of oxygen. Uptake and elimination rates were compared to weight and estimated (gill) exchange areas. The role of weight and its implications for extrapolations of bioconcentration parameters to other species and sizes will be discussed.« less

Effects of a helium/oxygen mixture on individuals' lung function and metabolic cost during submaximal exercise for participants with obstructive lung diseases.

PubMed

Häussermann, Sabine; Schulze, Anja; Katz, Ira M; Martin, Andrew R; Herpich, Christiane; Hunger, Theresa; Texereau, Joëlle

2015-01-01

Helium/oxygen therapies have been studied as a means to reduce the symptoms of obstructive lung diseases with inconclusive results in clinical trials. To better understand this variability in results, an exploratory physiological study was performed comparing the effects of helium/oxygen mixture (78%/22%) to that of medical air. The gas mixtures were administered to healthy, asthmatic, and chronic obstructive pulmonary disease (COPD) participants, both moderate and severe (6 participants in each disease group, a total of 30); at rest and during submaximal cycling exercise with equivalent work rates. Measurements of ventilatory parameters, forced spirometry, and ergospirometry were obtained. There was no statistical difference in ventilatory and cardiac responses to breathing helium/oxygen during submaximal exercise. For asthmatics, but not for the COPD participants, there was a statistically significant benefit in reduced metabolic cost, determined through measurement of oxygen uptake, for the same exercise work rate. However, the individual data show that there were a mixture of responders and nonresponders to helium/oxygen in all of the groups. The inconsistent response to helium/oxygen between individuals is perhaps the key drawback to the more effective and widespread use of helium/oxygen to increase exercise capacity and for other therapeutic applications.

Retinal oxygen distribution and the role of neuroglobin.

PubMed

Roberts, Paul A; Gaffney, Eamonn A; Luthert, Philip J; Foss, Alexander J E; Byrne, Helen M

2016-07-01

The retina is the tissue layer at the back of the eye that is responsible for light detection. Whilst equipped with a rich supply of oxygen, it has one of the highest oxygen demands of any tissue in the body and, as such, supply and demand are finely balanced. It has been suggested that the protein neuroglobin (Ngb), which is found in high concentrations within the retina, may help to maintain an adequate supply of oxygen via the processes of transport and storage. We construct mathematical models, formulated as systems of reaction-diffusion equations in one-dimension, to test this hypothesis. Numerical simulations show that Ngb may play an important role in oxygen transport, but not in storage. Our models predict that the retina is most susceptible to hypoxia in the regions of the photoreceptor inner segment and inner plexiform layers, where Ngb has the potential to prevent hypoxia and increase oxygen uptake by 30-40 %. Analysis of a simplified model confirms the utility of Ngb in transport and shows that its oxygen affinity ([Formula: see text] value) is near optimal for this process. Lastly, asymptotic analysis enables us to identify conditions under which the piecewise linear and quadratic approximations to the retinal oxygen profile, used in the literature, are valid.

Vertical migration of aggregated aerobic and anaerobic ammonium oxidizers enhances oxygen uptake in a stagnant water layer.

PubMed

Vlaeminck, Siegfried E; Dierick, Katleen; Boon, Nico; Verstraete, Willy

2007-07-01

Ammonium can be removed as dinitrogen gas by cooperating aerobic and anaerobic ammonium-oxidizing bacteria (AerAOB and AnAOB). The goal of this study was to verify putative mutual benefits for aggregated AerAOB and AnAOB in a stagnant freshwater environment. In an ammonium fed water column, the biological oxygen consumption rate was, on average, 76 kg O(2) ha(-1) day(-1). As the oxygen transfer rate of an abiotic control column was only 17 kg O(2) ha(-1) day(-1), biomass activity enhanced the oxygen transfer. Increasing the AnAOB gas production increased the oxygen consumption rate with more than 50% as a result of enhanced vertical movement of the biomass. The coupled decrease in dissolved oxygen concentration increased the diffusional oxygen transfer from the atmosphere in the water. Physically preventing the biomass from rising to the upper water layer instantaneously decreased oxygen and ammonium consumption and even led to the occurrence of some sulfate reduction. Floating of the biomass was further confirmed to be beneficial, as this allowed for the development of a higher AerAOB and AnAOB activity, compared to settled biomass. Overall, the results support mutual benefits for aggregated AerAOB and AnAOB, derived from the biomass uplifting effect of AnAOB gas production.

Uptake of phytodetritus by benthic foraminifera under oxygen depletion at the Indian Margin (Arabian Sea)

NASA Astrophysics Data System (ADS)

Enge, A. J.; Witte, U.; Kucera, M.; Heinz, P.

2013-09-01

Benthic foraminifera in sediments on the Indian margin of the Arabian Sea where the oxygen minimum zone (OMZ) impinges on the continental slope are exposed to particularly severe levels of oxygen depletion. Food supply for the benthic community is high but delivered in distinct pulses during upwelling and water mixing events associated with summer and winter monsoon periods. In order to investigate the response by benthic foraminifera to such pulsed food delivery under oxygen concentrations of less than 0.1 mL L-1 (4.5 μmol L-1), an in situ isotope labeling experiment (13C, 15N) was performed at the western continental slope of India at 540 m water depth (OMZ core region). The assemblage of living foraminifera (>125 μm) in the uppermost centimeter at this depth is characterized by an unexpectedly high population density of 3982 ind. 10 cm-2 and a strong dominance by few calcareous species. For the experiment, we concentrated on the nine most abundant taxa, which constitute 93% of the entire foraminifera population at 0-1 cm sediment depth. Increased concentrations of 13C and 15N in the cytoplasm indicate that all investigated taxa took up the labeled phytodetritus during the 4 day experimental phase. In total, these nine species had assimilated 113.8 mg C m-2 (17.5% of the total added carbon). The uptake of nitrogen by the three most abundant taxa (Bolivina aff. B. dilatata, Cassidulina sp., Bulimina gibba) was 2.7 mg N m-2 (2% of the total added nitrogen) and showed the successful application of 15N as tracer in foraminiferal studies. The short-term response to the offered phytodetritus varied largely among foraminiferal species with Uvigerina schwageri being by far the most important species in short-term processing whereas the most abundant taxa Bolivina aff. B. dilatata and Cassidulina sp. showed comparably low uptake of the offered food. We suggest that the observed species-specific differences are related to individual biomass of species and to specific feeding preferences. The high numbers of living foraminifera and their rapid response to deposited fresh phytodetritus demonstrate the importance of foraminifera in short-term carbon cycling under oxygen-depleted conditions. We propose that foraminifera at the studied site benefit from unique adaptations in their metabolisms to nearly anoxic conditions as well as from the exclusion of macrofauna and the resulting relaxation of competition for food and low predation pressure.

Bioavailability of methylmercury to Sacramento blackfish (Orthodon microlepidotus): Dissolved organic carbon effects

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

Choi, M.H.; Cech, J.J. Jr.; Lagunas-Solar, M.C.

1998-04-01

The effect of dissolved organic carbon (DOC) on methylmercury (MeHg) uptake across the gills of Sacramento blackfish (Orthodon microlepidotus) was investigated using the Hg-203 radioisotope. The efficiency of fish gills in extracting MeHg from water was measured using a McKim-type fish respirometer that separated exposure water from expired water. Blackfish gill ventilation and oxygen consumption rates remained constant, while Me{sup 203}Hg uptake was decreased significantly in the presence of DOC. Mean Me{sup 203}Hg extraction efficiency, uptake rate constant, and blood to inspired water ratio decreased 78%, 73%, and 63%, respectively, with 2 mg C/L of DOC, and 85%, 82%, andmore » 70% with 5 mg C/L DOC, compared to the Me{sup 203}Hg reference treatment group. Because respiratory parameters remained unchanged, reductions in Me{sup 203}Hg uptake indicate strong interactions between DOC and Me{sup 203}Hg Methyl{sup 203}Hg levels in fish gills, kidney, and spleen from 2 and 5 mg C/L were significantly lower than those observed from the reference treatment group. These reductions in uptake (bioavailability) support the hypothesis that trans-gill transport of Me{sup 203}Hg is inhibited when it is complexed by DOC in the aqueous medium, decreasing Me{sup 203}Hg uptake and accumulation in fish organs.« less

Dietary Factors Modulate Iron Uptake in Caco-2 Cells from an Iron Ingot Used as a Home Fortificant to Prevent Iron Deficiency

PubMed Central

Rodriguez-Ramiro, Ildefonso; Perfecto, Antonio; Fairweather-Tait, Susan J.

2017-01-01

Iron deficiency is a major public health concern and nutritional approaches are required to reduce its prevalence. The aim of this study was to examine the iron bioavailability of a novel home fortificant, the “Lucky Iron Fish™” (LIF) (www.luckyironfish.com/shop, Guelph, Canada) and the impact of dietary factors and a food matrix on iron uptake from LIF in Caco-2 cells. LIF released a substantial quantity of iron (about 1.2 mM) at pH 2 but this iron was only slightly soluble at pH 7 and not taken up by cells. The addition of ascorbic acid (AA) maintained the solubility of iron released from LIF (LIF-iron) at pH 7 and facilitated iron uptake by the cells in a concentration-dependent manner. In vitro digestion of LIF-iron in the presence of peas increased iron uptake 10-fold. However, the addition of tannic acid to the digestion reduced the cellular iron uptake 7.5-fold. Additionally, LIF-iron induced an overproduction of reactive oxygen species (ROS), similar to ferrous sulfate, but this effect was counteracted by the addition of AA. Overall, our data illustrate the major influence of dietary factors on iron solubility and bioavailability from LIF, and demonstrate that the addition of AA enhances iron uptake and reduces ROS in the intestinal lumen. PMID:28895913

Alteration in mitochondrial Ca(2+) uptake disrupts insulin signaling in hypertrophic cardiomyocytes.

PubMed

Gutiérrez, Tomás; Parra, Valentina; Troncoso, Rodrigo; Pennanen, Christian; Contreras-Ferrat, Ariel; Vasquez-Trincado, César; Morales, Pablo E; Lopez-Crisosto, Camila; Sotomayor-Flores, Cristian; Chiong, Mario; Rothermel, Beverly A; Lavandero, Sergio

2014-11-07

Cardiac hypertrophy is characterized by alterations in both cardiac bioenergetics and insulin sensitivity. Insulin promotes glucose uptake by cardiomyocytes and its use as a substrate for glycolysis and mitochondrial oxidation in order to maintain the high cardiac energy demands. Insulin stimulates Ca(2+) release from the endoplasmic reticulum, however, how this translates to changes in mitochondrial metabolism in either healthy or hypertrophic cardiomyocytes is not fully understood. In the present study we investigated insulin-dependent mitochondrial Ca(2+) signaling in normal and norepinephrine or insulin like growth factor-1-induced hypertrophic cardiomyocytes. Using mitochondrion-selective Ca(2+)-fluorescent probes we showed that insulin increases mitochondrial Ca(2+) levels. This signal was inhibited by the pharmacological blockade of either the inositol 1,4,5-triphosphate receptor or the mitochondrial Ca(2+) uniporter, as well as by siRNA-dependent mitochondrial Ca(2+) uniporter knockdown. Norepinephrine-stimulated cardiomyocytes showed a significant decrease in endoplasmic reticulum-mitochondrial contacts compared to either control or insulin like growth factor-1-stimulated cells. This resulted in a reduction in mitochondrial Ca(2+) uptake, Akt activation, glucose uptake and oxygen consumption in response to insulin. Blocking mitochondrial Ca(2+) uptake was sufficient to mimic the effect of norepinephrine-induced cardiomyocyte hypertrophy on insulin signaling. Mitochondrial Ca(2+) uptake is a key event in insulin signaling and metabolism in cardiomyocytes.