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Results 251 - 300 of 793
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Nedrow J M - - 2001
We have investigated the magnitude and duration of excess post-exercise oxygen consumption (EPOC) in a lizard following a single bout of vigorous exercise of 5-60 s, common activity durations for many ectothermic vertebrates. Desert iguanas (Dipsosaurus dorsalis) were run for 5 s, 15 s, 30 s, or 60 s. Oxygen ...
Sala E - - 2001
We hypothesized that impaired O2 transport plays a role in limiting exercise in patients with chronic renal failure (CRF). Six CRF patients (25 +/- 6 yr) and six controls (24 +/- 6 yr) were examined twice during incremental single-leg isolated quadriceps exercise. Leg O2 delivery (QO2(leg)) and leg O2 uptake ...
Domoto H - - 2001
BACKGROUND: The change in platelet count (PC) occurring during saturation diving has rarely been discussed. We set out to clarify the details of this change in PC, and its relationship with: i) the storage depth and duration of the saturation dive, and ii) the presence of decompression bubbles. METHODS: In ...
Noren S R - - 2001
Myoglobin is an important oxygen store for supporting aerobic diving in endotherms, yet little is known about its role during postnatal development. Therefore, we compared the postnatal development of myoglobin in marine endotherms that develop at sea (cetaceans) to those that develop on land (penguins and pinnipeds). We measured myoglobin ...
Tetzlaff K - - 2001
Increasing popularity of sports diving makes it likely that subjects with allergic respiratory diseases will be involved in diving with self contained underwater breathing apparatus (scuba). The present study evaluated the effects of a single scuba-dive on pulmonary function in subjects with respiratory atopy. Specific airways conductance (sGaw), residual volume ...
Wilmshurst P - - 2001
A relationship between migraine with aura and the presence of right-to-left shunts has been reported in two studies. Right-to-left shunts are also associated with some forms of decompression illness. While conducting research in divers with decompression illness, it was our impression that divers with a large shunt often had a ...
Träger K - - 2001
OBJECTIVE: We compared the effects of thromboxane receptor antagonist and synthase inhibitor DTTX30 on systemic and liver blood flow, oxygen (O2) exchange and energy metabolism during 24 h of hyperdynamic endotoxemia with untreated endotoxemia. DESIGN: Prospective, randomized, experimental study with repeated measures. SETTING: Investigational animal laboratory. SUBJECTS: Twenty-seven domestic pigs: ...
Thorsen E - - 2001
A reduction in hemoglobin concentration has been consistently reported after deep saturation dives, whereas reductions in thrombocyte counts and changes in biochemical parameters specific for liver function have been reported after some dives. In this study the contribution of exposure to hyperoxia to these changes were studied. Hemoglobin concentration, blood ...
Lee J W - - 2000
The objective of this study was to investigate the effect of singlet oxygen ((1)O2) scavengers on functional recovery and ascorbyl free radical (AFR) formation in isolated ischemic rat hearts. Hearts were subjected to 40 min. of global ischemia followed by 30 min. of reperfusion. Hemodynamics were measured as heart rate ...
Gross B D - - 2000
An intraluminal membrane oxygenator (IMO) prototype was surgically inserted in the ileum and evaluated as a method of supporting systemic oxygenation in an acutely hypoxemic porcine model. Animals were assigned randomly to the test (n = 12) or the control (n = 8) groups, which underwent identical protocols with the ...
Le Boeuf B J - - 2000
All underwater activities of diving mammals are constrained by the need for surface gas exchange. Our aim was to measure respiratory rate (fb) and heart rate (fh) at the surface between dives in free-ranging northern elephant seals Mirounga angustirostris. We recorded fb and fh acoustically in six translocated juveniles, 1.8-2. ...
Carturan D - - 2000
The aim of this study was to assess the effect of the ascent rate on the production of venous circulating bubbles during the decompression following a recreational dive. Twenty-eight recreational divers performed two open water dives at 35 m during 25 minutes. Ascent rate up to the decompression stop was ...
Wohlgemuth S E - - 2000
We examined the effects of hypoxia and sulphide levels on the ventilatory activity of Arenicola marina and determined whether ventilation compensates for oxygen deficiency and affects the mode of energy provision. A. marina ventilated intermittently, irrespective of ambient P(O2) and sulphide concentration. The ventilation rate was 28.5+/-16 ml h(-1) g(-1) ...
Fenger C K - - 2000
OBJECTIVE: To determine components of the increase in oxygen consumption (VO2) and evaluate determinants of hemoglobin saturation (SO2) during incremental treadmill exercise in unfit horses. ANIMALS: 7 unfit adult mares. PROCEDURES: Horses performed 1 preliminary exercise test (EXT) and 2 experimental EXT. Arterial and mixed venous blood samples and hemodynamic ...
Lodge J K - - 2000
Atherosclerotic plaques form in the arterial intima, where low density lipoprotein (LDL) is thought to be oxidatively modified at sites which may contain catalytic amounts of copper in the presence of low O2 tension. We have investigated O2 consumption during LDL peroxidation induced by Cu2+ ions in vitro and found ...
Hawkins P A - - 2000
The relationship between heart rate (f(H)) and rate of oxygen consumption (V(O2)) was established for a marine diving bird, the common eider duck (Somateria mollissima), during steady-state swimming and running exercise. Both variables increased exponentially with speed during swimming and in a linear fashion during running. Eleven linear regressions of ...
Breen P H - - 2000
Traditionally, measurement of pulmonary O2 uptake uses mass balance of N2 to correct for differences between inspired and expired volume (V) due to temperature (T) and relative humidity (RH). Often during anesthesia, N2 balance cannot be invoked due to high inspired O2 fraction (FIO2) or nonsteady state conditions. Then, O2 ...
Hicks J W - - 2000
The principal function of the cardiopulmonary system is the precise matching of O(2) and CO(2) transport to the metabolic requirements of different tissues. In some ecothermic vertebrates (amphibians and reptiles), vdot (O2) increases dramatically following feeding. Factorial increments in vdot (O2) range from 1.7 to 44 times above resting rates, ...
Beck C A - - 2000
Phocid seals go through dramatic seasonal changes in body mass and composition as a result of the spatial and temporal separation of foraging, reproduction and moulting. These changes in body fat content and body mass result in seasonal changes in buoyancy, which in turn may influence diving behaviour. We examined ...
Harms C A - - 2000
PURPOSE: We have recently reported that many healthy habitually active women experience exercise induced arterial hypoxemia (EIAH). We questioned whether EIAH affected VO2max in this population and whether the effect was similar to that reported in men. METHODS: Twenty-five healthy young women with widely varying fitness levels (VO2max, 56.7 +/- ...
Sawada S - - 2000
Oxygen transfer across a single cotyledon of the human placenta was assessed by using three different perfusates in the maternal circuit: 1) M-199 culture medium, 2) human adult red blood cells (RBCs), and 3) perflubron. These maternal circuit perfusates were oxygenated with a membrane oxygenator. RBCs were perfused on the ...
Epstein C D - - 2000
OBJECTIVE: The purpose of this study was to compare the measurements of whole body oxygen consumption determined by the Fick method and by indirect calorimetry in mechanically ventilated patients with multiple trauma. DESIGN: A prospective, correlational, within-subjects design. SETTING: Surgical intensive care unit of a Level I trauma center. PATIENTS: ...
Bohnhorst B - - 2000
OBJECTIVE: Pulse oximeters are increasingly used for patient monitoring; however, they are traditionally very prone to motion artifact. Newly developed instruments have lower false alarm rates. We wanted to know whether this is achieved at the expense of an increased proportion of false negative alarms such as missed or delayed ...
Shen W - - 2000
Our previous studies uncovered an inhibitory effect of nitric oxide (NO) on leg skeletal muscle respiration in dogs at rest. The role of NO in the modulation of O2 consumption and O2 extraction in hindlimb muscle during elevated metabolic states was investigated in chronically instrumented dogs while walking and at ...
Conley K E - - 2000
Myoglobin (Mb) is a large protein that reversibly binds oxygen in the muscle cell and is thought to be critical for O2 supply to the mitochondria during exercise. The role of Mb in aerobic function is evaluated based on the physical properties of Mb as an O2 carrier and experimental ...
Hays GC - - 2000
For six green turtles, Chelonia mydas, that had nested on Ascension Island in the South Atlantic, we used time-depth recorders to examine their diving behaviour during the subsequent internesting interval (10-12 days). All the turtles performed dives where they remained at a fixed depth for a long period, surfaced briefly ...
Lieberman J A - - 2000
BACKGROUND: The "critical" level of oxygen delivery (DO2) is the value below which DO2 fails to satisfy the metabolic need for oxygen. No prospective data in healthy, conscious humans define this value. The authors reduced DO2 in healthy volunteers in an attempt to determine the critical DO2. METHODS: With Institutional ...
Barstow T J - - 2000
We recently reported that a higher percentage of type I fibres in vastus lateralis and a greater peak oxygen uptake (O2) were associated with a greater initial rise in O2 (O2 /W, where W is work rate) following the onset of heavy constant power output exercise (above the lactate threshold, ...
Richardson R S - - 2000
Recent investigations into the determinants of skeletal muscle maximal oxygen consumption (VO2) have provided further evidence regarding the role of O2 supply and demand in governing exercise metabolism. Specifically, four studies utilizing both animal and human exercise models are highlighted here: 1) the role of the diffusive O2 component was ...
Bassett D R DR - - 2000
In the exercising human, maximal oxygen uptake (VO2max) is limited by the ability of the cardiorespiratory system to deliver oxygen to the exercising muscles. This is shown by three major lines of evidence: 1) when oxygen delivery is altered (by blood doping, hypoxia, or beta-blockade), VO2max changes accordingly; 2) the ...
MacDonald M J - - 2000
The purpose of this study was to examine the interactions of adaptations in O2 transport and utilization under conditions of altered arterial O2 content (CaO2), during rest to exercise transitions. Simultaneous measures of alveolar (VO2alv) and leg (VO2mus) oxygen uptake and leg blood flow (LBF) responses were obtained in normoxic ...
Piiper J - - 1999
To quantify the role of factors determining O2 availability to exercising muscle, a model previously devised for the analysis of O2 uptake in lungs is used. With the variables: (1) blood flow (Q); (2) slope of the blood O2 equilibrium curve (betaO2); and (3) muscle blood-tissue O2 diffusing capacity (D(O2)), ...
Ishihara H - - 1999
The intervertebral disc is the largest asvacular structure in the body; consequently, there are steep gradients in O2 concentration, with PO2 falling to as low as 1% O2 in the centre of the disc. We investigated the effect of O2 concentration on the rates of O2 consumption, lactate production, and ...
Peltonen J E - - 1999
This study was conducted to determine whether arterial desaturation would occur at submaximal workloads in highly trained endurance athletes and whether saturation is affected by the fraction of oxygen in inspired air (F(I)O2). Six highly trained endurance athletes (5 women and 1 man, aged 25+/-4 yr, VO2max 71.3+/-5.0 ml x ...
Williams T M - - 1999
During diving, marine mammals must rely on the efficient utilization of a limited oxygen reserve sequestered in the lungs, blood and muscles. To determine the effects of exercise and apnea on the use of these reserves, we examined the physiological responses of adult bottlenose dolphins (Tursiops truncatus) trained to breath-hold ...
Skrovan R C - - 1999
During diving, marine mammals must balance the conservation of limited oxygen reserves with the metabolic costs of swimming exercise. As a result, energetically efficient modes of locomotion provide an advantage during periods of submergence and will presumably increase in importance as the animals perform progressively longer dives. To determine the ...
Nielsen H B - - 1999
The combined effects of hyperventilation and arterial desaturation on cerebral oxygenation (ScO2) were determined using near-infrared spectroscopy. Eleven competitive oarsmen were evaluated during a 6-min maximal ergometer row. The study was randomized in a double-blind fashion with an inspired O2 fraction of 0.21 or 0.30 in a crossover design. During ...
Buck D - - 1999
PURPOSE: The accumulated O2, calculated by an extrapolation procedure from measurements of the O2 uptake at moderate powers, has been suggested as a measure of the anaerobic energy release during high intensity exercise. While some suggest that repeated 10-min bouts are required to establish the relationships in question, other use ...
Pedersen P K - - 1999
We examined the influence of hyperoxia on peak oxygen uptake (VO2peak) and peripheral gas exchange during exercise with the quadriceps femoris muscle. Young, trained men (n=5) and women (n=3) performed single-leg knee-extension exercise at 70% and 100% of maximum while inspiring normal air (NOX) or 60% O2 (HiOX). Blood was ...
Hensel M - - 1999
Pulmonary oxygen consumption (V(O2)pulm) is believed to be increased in patients with lung infection. In the present study, VO2pulm was estimated from the difference between total oxygen consumption measured with indirect calorimetry (V(O2)cal) and oxygen consumption assessed with the reverse Fick method (V(O2)Fick). Seventy-five patients requiring mechanical ventilation were included, ...
Weibel E R - - 1999
The lung is characterized by its diffusing capacity for oxygen, DLO2, which is estimated from morphometric information as a theoretical capacity. It is determined by the large gas exchange surface, the thin tissue barrier, and the amount of capillary blood. The question is asked whether DLO2 could be a limiting ...
Warburton D E - - 1999
OBJECTIVE: To determine whether plasma volume expansion (PVexp) in elite endurance-trained (ET) cyclists, who already possess both a high blood volume (BV) and a high VO2max, leads to further enhancements in their cardiac function, VO2max, and endurance performance (time to exhaustion at 95% VO2max). METHODS: Nine male ET cyclists (V02max ...
Amirmansour C - - 1999
1. Experiments were designed to explore the effects of nitric oxide (NO) donors on generation of superoxide (O2.-) and peroxynitrite (ONOO-) in rabbit aortic rings. 2. Following inhibition of endogenous superoxide dismutase (SOD), significant basal release of O2.- was revealed (0.9 +/- 0.01 x 10(-12) mol min-1 mg-1 tissue). Generation ...
Ogita F - - 1999
PURPOSE: Swimmers swim faster using hand paddles. In this study the effect of maximal performance using hand paddles on aerobic and anaerobic energy release during supramaximal swimming was examined by comparing the maximal accumulated O2 deficit, and the aerobic and anaerobic energy release during exhaustive swimming with paddles (P) to ...
de Groot B - - 1999
We investigated the role of myoglobin (Mb) in supplying O2 to mitochondria during transitions in cardiac workload. Isovolumic rabbit hearts (n = 7) were perfused retrogradely with hemoglobin-free Tyrode solution at 37 degrees C. Coronary venous O2 tension was measured polarographically, and tissue oxygenation was measured with two-wavelength near-infrared spectroscopy ...
Mejia R - - 1999
A target heart rate (THR) is the traditional method to prescribe and monitor exercise training intensity in healthy individuals. However, patients with chronic obstructive pulmonary disease (COPD) are limited by ventilatory impairment and dyspnea rather than cardiovascular factors. An alternative approach is to use dyspnea ratings as a target for ...
Ponganis P J - - 1999
To compare the diving capacities of juvenile and adult emperor penguins Aptenodytes forsteri, and to determine the physiological variables underlying the diving ability of juveniles, we monitored diving activity in juvenile penguins fitted with satellite-linked time/depth recorders and examined developmental changes in body mass (Mb), hemoglobin concentration, myoglobin (Mb) content ...
Tschakovsky M E - - 1999
Considerable debate surrounds the issue of whether the rate of adaptation of skeletal muscle O2 consumption (QO2) at the onset of exercise is limited by 1) the inertia of intrinsic cellular metabolic signals and enzyme activation or 2) the availability of O2 to the mitochondria, as determined by an extrinsic ...
McCanse W - - 1999
Systemic O2 transport during maximal exercise at different inspired PO2 (PIO2) values was studied in sodium cyanate-treated (CY) and nontreated (NT) rats. CY rats exhibited increased O2 affinity of Hb (exercise O2 half-saturation pressure of Hb = 27.5 vs. 42.5 Torr), elevated blood Hb concentration, pulmonary hypertension, blunted hypoxic pulmonary ...
Rice A J - - 1999
A group of 15 competitive male cyclists [mean peak oxygen uptake, VO2peak 68.5 (SEM 1.5 ml x kg(-1) x min(-1))] exercised on a cycle ergometer in a protocol which began at an intensity of 150 W and was increased by 25 W every 2 min until the subject was exhausted. ...
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