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Results 351 - 400 of 973
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Goldstein N - - 2002
In this review evidence for the presence of the anion radical O2(-*) in atmospheric air is considered, and the biological activity of superoxide and negative air ions is compared. Various aspects of the biological effect of superoxide and other reactive oxygen species contained in air at the cell, tissue, and ...
Tusseau-Vuillemin M H - - 2002
Two different re-oxygenation techniques (aeration and hydrogen peroxide addition) were compared in respirometric experiments. As similar results were obtained in both cases, it was concluded that the addition of hydrogen peroxide does not modify the oxygen uptake rate of the biomass, under either endogenous or feeding conditions. It was hypothesized ...
Walamies Markku A - - 2002
Eighteen generally fit clinical patients were monitored with pulse oximetry. Mean oxygen saturation levels were lower (P<0.05) during oesophageal manometry (97.7-97.3%) than before it (98.3%). Fourteen out of seventeen (successful) traces had short 4-8% desaturation episodes, and in worst cases there were 8-9 episodes. It seems, therefore, that even patients ...
Hütter Eveline - - 2002
Oxygen kinetics in fibroblasts was biphasic. This was quantitatively explained by a major mitochondrial hyperbolic component in the low-oxygen range and a linear increase of rotenone- and antimycin A-inhibited oxygen consumption in the high-oxygen range. This suggests an increased production of reactive oxygen species and oxidative stress at elevated, air-level ...
David O - - 2002
Nine carriers of beta-abnormal haemoglobins with increased oxygen affinity (Hb X) were examined. Their oxygen dissociation curves from whole blood were more or less left-shifted, with six of nine also characterized by biphasism. This refers to an 'inflection point' usually positioned at about 50-60% of Hb O(2) saturation, commonly believed ...
Pham Tuan H - - 2002
Hemorrhagic hypovolemia and inotropic agent administration were used to manipulate cardiac output (CO) and oxygen delivery in rabbits to investigate the correlation between noninvasive frequency domain photon migration (FDPM) spectroscopy and invasive hemodynamic monitoring parameters. Frequency-domain photon migration provides quantitative measurements of light absorption and reduced scattering (mu(a) and mu(s)(prime ...
Hink J - - 2001
The basic mechanisms behind the pharmacologic effects of hyperbaric oxygen therapy are not clear. Reactive oxygen metabolites are generally associated with the adverse reactions to hyperbaric oxygen exposure but they are also believed to be involved in the antibacterial effects of this therapy. The possibility that reactive oxygen metabolites are ...
Wijkstra P J - - 2001
While there is broad agreement about who should receive long-term oxygen therapy (LTOT), there is little information available on how clinicians should decide on the oxygen prescription itself, at rest, during sleep and during exercise. The authors describe the results of an international survey that was undertaken to compare how ...
Gnaiger E - - 2001
Oxygen limitation is generally considered as impairment of mitochondrial respiration under hypoxia and ischemia. Low intracellular oxygen levels under normoxia, however, imply mild oxygen limitation, provide protection from oxidative stress, and result from economical strategies for oxygen transport through the respiratory cascade to cytochrome c oxidase. Both perspectives relate to ...
Janz C - - 2001
Neuronal activation leads to an increase in the local cortical perfusion. The exact regulatory mechanisms leading to these changes are still unknown. To elucidate the role of oxygen in the initial hemodynamic regulation, a disactivation paradigm was performed with fMRI. A stimulus was applied following a previous extended activation in ...
Schumacher Y O - - 2001
Maximal oxygen uptake is the major performance limiting factor in endurance sports. Sophisticated training methods have been developed to increase this variable. On the other hand, attempts have been made to improve maximal oxygen uptake by artificial means: blood doping and the misuse of recombinant human erythropoietin have beneficial effects ...
McGuire B J - - 2001
Oxygen transport from capillaries to exercising skeletal muscle is studied by use of a Krogh-type cylinder model. The goal is to predict oxygen consumption under conditions of high demand, on the basis of a consideration of transport processes occurring at the microvascular level. Effects of the decline in oxygen content ...
Wiechert U - - 2001
We have determined the abundances of 16O, 17O, and 18O in 31 lunar samples from Apollo missions 11, 12, 15, 16, and 17 using a high-precision laser fluorination technique. All oxygen isotope compositions plot within +/-0.016 per mil (2 standard deviations) on a single mass-dependent fractionation line that is identical ...
Baumgarten A - - 2001
Washed cells of Desulfovibrio vulgaris strain Marburg (DSM 2119) reduced oxygen to water with H(2) as electron donor at a mean rate of 253 nmol O(2) min(-1) (mg protein)(-1). After separating the periplasm from the cells, more than 60% of the cytochrome c activity and 90% of the oxygen-reducing activity ...
Neary J P - - 2001
In this study we examined the oxygenation trend of the vastus medialis muscle during sustained high-intensity exercise. Ten cyclists performed an incremental cycle ergometer test to voluntary exhaustion [mean (SD) maximum oxygen uptake 4.29 (0.63) l x min(-1); relative to body mass 60.8 (2.4) ml x kg(-1)min(-1)] and a simulated ...
Arieli R - - 2001
Central nervous system (CNS) oxygen toxicity can occur as convulsions and loss of consciousness when hyperbaric oxygen is breathed in diving and hyperbaric medical therapy. Lin and Jamieson (J Appl Physiol 75: 1980-1983, 1993) reported that humidity in the inspired gas enhances CNS oxygen toxicity. Because alveolar gas is fully ...
Hoffmann U - - 2001
As the use of oxygen enhances the resorption of gas bubbles in decompression illness, it is recommended and generally accepted that the inspired oxygen concentration in emergency treatment of diving accidents has to be as close to 100% as possible. Therefore, several emergency oxygen devices are offered to the diving ...
Gallaugher P E - - 2001
To examine cardiorespiratory plasticity, cardiovascular function, oxygen consumption, oxygen delivery and osmotic balance were measured at velocities up to critical swimming speed (Ucrit) in seawater-adapted chinook salmon. We used two groups of fish. The control group had swum continuously for 4 months at a low intensity (0.5 BLs(-1)) and the ...
Tijerina M - - 2001
Photosensitizers, light-sensitive compounds, become activated upon illumination with a specific wavelength of light generating cytotoxic oxygen species. Due to the short half-life of singlet oxygen, the subcellular site of localization and excitation affects the type of cellular damage produced as well as cellular responses to different types of photodamage created ...
Froget G - - 2001
The use of heart rate to estimate field metabolic rate has become a more widely used technique. However, this method also has some limitations, among which is the possible impact that several variables such as sex, body condition (i.e. body fat stores) and/or inactivity might have on the relationship between ...
Sakamoto T - - 2001
Near-infrared spectroscopy assessment of cytochrome oxygenation could be a valuable technique to monitor cerebral intraneuronal oxygen delivery during cardiopulmonary bypass. However, the validity of the cytochrome signal has been questioned as it could easily be overwhelmed by the Hb signal. Five- to six-week-old control piglets (n = 5) underwent cardiopulmonary ...
Timmins G S - - 2001
Endogenous reductants such as hydrogen sulfide and alkylthiols provided free radical scavenging systems during the early evolution of life. The development of oxygenic photosynthesis spectacularly increased oxygen levels, and ancient life forms were obliged to develop additional antioxidative systems. We develop here the hypothesis of how "prototypical" bioluminescent reactions had ...
Bengtsson J - - 2001
BACKGROUND: "Ideal" alveolar oxygen tension (PAO2) is a calculated entity and the alveolar-arterial oxygen tension difference (PA-aO2) is used to evaluate gas exchange function of the lungs. Accurate calculations of PAO2 necessitate measurements of the respiratory exchange ratio (RER), which is less frequently done, and most often approximations are made. ...
Bouwer S T - - 2001
The purpose of this study was to verify the concept of non-equilibrium facilitated oxygen diffusion. This work succeeds our previous study, where facilitated oxygen diffusion by hemoglobin was measured at conditions of chemical equilibrium, and which yielded diffusion coefficients of hemoglobin and of oxygen. In the present work chemical non-equilibrium ...
Saugstad O D - - 2001
Since the discovery of retrolental fibroplasia, and the role of oxygen in its development, oxygen has been considered a double-edged sword in neonatal medicine, the utmost care being exercised in order not to give too much oxygen (1). However, the important observation that hypoxaemia might induce pulmonary vasoconstriction (2) and ...
Holzer K - - 2001
The purpose of the study was to characterize oxygen radical generation by emigrated, intraabdominal and circulating polymorphonuclear leukocytes (ePMNLs and cPMNLs) during peritonitis, as well as to assess any differences between oxygen radical production in patients with low Mannheim peritonitis index (MPI < 26, group 1) or high Mannheim peritonitis ...
Mills C E - - 2001
A purification procedure for flavohaemoglobin Hmp (NO oxygenase) is described that gives high yields of protein with equistoichiometric haem and FAD contents. H(2)O(2) accumulated on NADH oxidation by the purified protein and in cell extracts with elevated Hmp contents. H(2)O(2) probably arose by dismutation from superoxide, which was also detectable ...
van Bommel - - 2001
BACKGROUND: A critical point in oxygen supply for microvascular oxygenation during normovolemic hemodilution has not been identified. The relation between organ microvascular oxygen partial pressure (microPO2) and organ oxygen consumption (VO2) during a decreasing oxygen delivery (DO2) is not well understood. The present study was designed to determine the systemic ...
Smets B F - - 2001
Transformation of 2,4-dinitrotoluene (2,4-DNT) by Alcaligenes JS867 under varying degrees of oxygen limitation was examined. Complete 2,4-DNT removal was observed under oxygen excess with near stoichiometric release (83%) of nitrite. Average kinetic parameters were estimated based on a dual-Monod biokinetic model with 2,4-DNT and O2 as growth limiting substrates. The ...
Durak I - - 2001
BACKGROUND: Volatile anesthetics (VAs) have been shown to enhance myocardial recovery during reperfusion, the mechanism of which has not been clarified yet. It has been supposed that this effect of VAs may appear through antioxidative mechanisms. METHODS: Thirty guinea pigs were used in the study. There were three groups with ...
Schell D J - - 2001
The production of low-cost cellulase enzyme is a key step in the development of an enzymatic-based process for conversion of lignocellulosic biomass to ethanol. Although abundant information is available on cellulase production, little of this work has examined oxygen transfer. We investigated oxygen transfer during the growth of Trichoderma reesei, ...
Kjaersgaard M - - 2000
OBJECTIVE: To evaluate the effect of supplemental oxygen on postoperative cardiovascular response to submaximal exercise. DESIGN: Randomised, controlled study. SETTING: University hospital, Denmark. SUBJECTS: 16 patients having major abdominal operations. INTERVENTIONS: A submaximal exercise test (heart rate up to 120 min(-1)) done twice on the third day after operation. Patients ...
Sheafor E A - - 2000
The hypothesis that the lungless salamander Desmognathus fuscus responds actively to hypoxia was tested. Patterns of buccal movements [apneic period duration, the duration (min h(-)(1)) of buccal pumping and buccal pumping frequency], heart rate and metabolic rate (rates of oxygen uptake and carbon dioxide output) were determined during a control ...
Nakata K - - 2000
Two types small and efficient ECMO oxygenators were developed utilizing the most up to date hollow fiber technology. Newly silicone hollow fibers possess sufficient mechanical strength while maintaining ultra thin walls of 50 micro meter. Two types of oxygenators were made with this fiber. The fiber length for the type ...
Tschischka K - - 2000
The rates of oxygen uptake of the marine polychaete Nereis pelagica and the bivalve Arctica islandica depend on the availability of ambient oxygen. This is manifest both at the tissue level and in isolated mitochondria studied between oxygen tensions (P(O2)) of 6.3 and 47.6 kPa (47-357 mmHg). Oxyconformity was found ...
Nakamura M - - 2000
Mixed venous oxygen saturation (SvO2) has been proposed as one of the suitable parameters for physiologic control of a total artificial heart (TAH). To establish the practical application of SvO2, we investigated the response of cardiac output (CO) and SvO2 to step-loaded exercise. A normal calf was surgically equipped with ...
Sigalevich P - - 2000
A chemostat coculture of the sulfate-reducing bacterium Desulfovibrio oxyclinae and the facultatively aerobic heterotroph Marinobacter sp. strain MB was grown for 1 week under anaerobic conditions at a dilution rate of 0.05 h(-1). It was then exposed to an oxygen flux of 223 micromol min(-1) by gassing the growth vessel ...
Guyatt G H - - 2000
OBJECTIVE: Almost every country in the developed world has a domiciliary oxygen program. Whether recipients meet program criteria has not been rigorously studied. DESIGN: Cross-sectional survey. PARTICIPANTS: Two hundred thirty-seven patients receiving domiciliary oxygen in the Ontario Ministry of Health Home Oxygen Program (HOP). METHODS: A respiratory therapist visited the ...
Aquino-Parsons C - - 2000
BACKGROUND AND PURPOSE: To assess the effect of inhalation of various high oxygen content gases (HOCG) with different carbon dioxide concentrations on the tumour oxygen tension in patients with primary gynaecological malignancies. MATERIALS AND METHODS: Tumour oxygen tension was assessed on two protocols in those patients with locally advanced visible ...
Gnaiger E - - 2000
Mitochondria are confronted with low oxygen levels in the microenvironment within tissues; yet, isolated mitochondria are routinely studied under air-saturated conditions that are effectively hyperoxic, increase oxidative stress, and may impair mitochondrial function. Under hypoxia, on the other hand, respiration and ATP supply are restricted. Under these conditions of oxygen ...
Bangsbo J - - 2000
The present study examined the onset and the rate of rise of muscle oxidation during intense exercise in humans and whether oxygen availability limits muscle oxygen uptake in the initial phase of intense exercise. Six subjects performed 3 min of intense one-legged knee-extensor exercise [65.3 +/- 3.7 (means +/- SE) ...
Plaut I - - 2000
Specimens of the euryhaline cyprinodontid fish, Aphanius dispar, collected in salt ponds, were acclimated to salinities of <1 (freshwater), 35 (seawater), 70, 105, and 140 ppt for 4 wk before measurement of oxygen consumption, critical swimming speed, and routine activity level. Oxygen consumption was similar in <1, 35, and 70 ...
Baba R - - 2000
Oxygen uptake efficiency slope is a new index of cardiorespiratory functional reserve derived from the logarithmic relation between oxygen uptake (VO(2)) and minute ventilation during incremental exercise. The oxygen uptake efficiency slope represents how effectively oxygen is extracted and taken into the body from the air, and then ventilated. The ...
Revill S M - - 2000
In a prospective, randomized study we examined the effect of (i) ambulatory oxygen and (ii) a portable, inspiratory pressure support (IPS) device on the endurance shuttle walk test (ESWT) in patients with severe chronic obstructive pulmonary disease (COPD). Ten outpatients [median (range) FEV1 0.60 l(0.35, 1.45)] performed the ESWT under ...
Agarwal K S - - 2000
The text book of Pediatric Advanced Life Support of the American Heart Association recommends that a reservoir is used with a self inflating bag valve device. The figure in the book suggests that if such a device is connected to an oxygen supply, the oxygen will fill the bag first ...
Eckmann D M - - 2000
Tracheal insufflation of oxygen has at least three major uses for chronic oxygen supplementation through a percutaneous catheter, it is an adjunctive measure to enhance gas exchange during mechanical ventilation, and it provides an emergency therapy for oxygen delivery with upper airway obstruction. In this article the mechanisms of gas ...
Reybrouck T - - 2000
OBJECTIVE: To assess the relation between exercise intensity and oxygen uptake during graded exercise in paediatric patients who underwent surgical repair of congenital heart disease, and to compare it with conventional measures of aerobic exercise function. DESIGN: Cross sectional study. Exercise testing was performed on a treadmill and gas exchange ...
Berkowitz B A - - 2000
PURPOSE: To test the hypothesis that after supplemental oxygen recovery (SOR) in the newborn rat model of retinopathy of prematurity (ROP) the preretinal neovascular (NV) incidence and severity are decreased and the panretinal oxygenation ability is improved. METHODS: Newborn rats were first raised in either room air (controls) or variable ...
Arthur P G - - 2000
Oxygen conformance can be described as the ability to reduce energy demand, and hence oxygen consumption, in response to a decline in oxygen availability without a decrease in the concentration of ATP. It has been proposed that oxygen conformance may enhance cellular survival at low oxygen concentrations. We demonstrate that ...
Mitra S - - 2000
Phosphorescence quenching of certain metalloporphyrins is used to measure tissue and microvascular pO(2). Oxygen quenching of metalloporphyrin triplet states creates singlet oxygen, which is highly reactive in biological systems, and these oxygen-consuming reactions are capable of perturbing tissue oxygenation. Kinetics of photochemical oxygen consumption were measured for a Pd-porphyrin in ...
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