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Oxygen Uptake (oxygen + uptake)

Distribution by Scientific Domains
Medical Sciences51%
Life Sciences41%
Earth and Environmental Science3%
3 Other Domains5%
Distribution within Medical Sciences
Pediatrics11%
General & Internal Medicine7%
Diabetes5%
14 Other Subdomains62%

Kinds of Oxygen Uptake

  • maximal oxygen uptake
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  • maximum oxygen uptake
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  • peak oxygen uptake
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    Terms modified by Oxygen Uptake

  • oxygen uptake rate
    		•

    Selected Abstracts

    Modelling the Influence of Age, Body Size and Sex on Maximum Oxygen Uptake in Older Humans

    EXPERIMENTAL PHYSIOLOGY, Issue 2 2000
    Patrick J. Johnson
    The purpose of this study was to describe the influence of body size and sex on the decline in maximum oxygen uptake (V,O2,max) in older men and women. A stratified random sample of 152 men and 146 women, aged 55-86 years, was drawn from the study population. Influence of age on V,O2,max, independent of differences in body mass (BM) or fat-free mass (FFM), was investigated using the following allometric model: V,O2,max= BMb (or FFMb) exp(a + (c × age) + (d × sex)) [epsilon]. The model was linearised and parameters identified using standard multiple regression. The BM model explained 68.8% of the variance in V,O2,max. The parameters (± s.e.e., standard error of the estimate) for lnBM (0.563 ± 0.070), age (-0.0154 ± 0.0012), sex (0.242 ± 0.024) and the intercept (-1.09 ± 0.32) were all significant (P < 0.001). The FFM model explained 69.3% of the variance in V,O2,max, and the parameters (± s.e.e) lnFFM (0.772 ± 0.090), age (-0.0159 ± 0.0012) and the intercept (-1.57 ± 0.36) were significant (P < 0.001), while sex (0.077 +/, 0.038) was significant at P = 0.0497. Regardless of the model used, the age-associated decline was similar, with a relative decline of 15% per decade (0.984 exp(age)) in V,O2,max in older humans being estimated. The study has demonstrated that, for a randomly drawn sample, the age-related loss in V,O2,max is determined, in part, by the loss of fat-free body mass. When this factor is accounted for, the loss of V,O2,max across age is similar in older men and women. [source]

    Oxygen Uptake and Involvement of Superoxide Radicals upon Photolysis of Ketones in Air-saturated Aqueous Alcohol, Formate, Amine or Ascorbic Acid Solutions

    PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2006
    Helmut Görner
    ABSTRACT The photolysis of acetophenone, benzophenone, 4-carboxy-benzophenone and benzil was studied in air-saturated aqueous solution in the presence of alcohols. The overall reaction is an oxidation of 2-propanol to acetone. The quantum yield of oxygen uptake (, -O2) increases with increasing 2-propanol concentration up to 0.9. The photoreaction can also be initiated by quenching of the ketone triplet state by ascorbic acid, formate or an amine e.g. triethylamine. Subsequent reactions of the involved radicals with oxygen yield the super-oxide radical and eventually hydrogen peroxide. For the ketones in the presence of 3,30 mM ascorbic acid or triethylamine , -O2= 0.3,0.9. The specific properties of ketones, including 4-methoxyacetophenone and 2-acetonaphthone, the radicals involved and the pH and concentration dependences of , -O2 are discussed. [source]

    Impaired oxygen kinetics in beta-thalassaemia major patients

    ACTA PHYSIOLOGICA, Issue 3 2009
    I. Vasileiadis
    Abstract Aim:, Beta-thalassaemia major (TM) affects oxygen flow and utilization and reduces patients' exercise capacity. The aim of this study was to assess phase I and phase II oxygen kinetics during submaximal exercise test in thalassaemics and make possible considerations about the pathophysiology of the energy-producing mechanisms and their expected exercise limitation. Methods:, Twelve TM patients with no clinical evidence of cardiac or respiratory disease and 10 healthy subjects performed incremental, symptom-limited cardiopulmonary exercise testing (CPET) and submaximal, constant workload CPET. Oxygen uptake (Vo2), carbon dioxide output and ventilation were measured breath-by-breath. Results:, Peak Vo2 was reduced in TM patients (22.3 ± 7.4 vs. 28.8 ± 4.8 mL kg,1 min,1, P < 0.05) as was anaerobic threshold (13.1 ± 2.7 vs. 17.4 ± 2.6 mL kg,1 min,1, P = 0.002). There was no difference in oxygen cost of work at peak exercise (11.7 ± 1.9 vs. 12.6 ± 1.9 mL min,1 W,1 for patients and controls respectively, P = ns). Phase I duration was similar in TM patients and controls (24.6 ± 7.3 vs. 23.3 ± 6.6 s respectively, P = ns) whereas phase II time constant in patients was significantly prolonged (42.8 ± 12.0 vs. 32.0 ± 9.8 s, P < 0.05). Conclusion:, TM patients present prolonged phase II on-transient oxygen kinetics during submaximal, constant workload exercise, compared with healthy controls, possibly suggesting a slower rate of high energy phosphate production and utilization and reduced oxidative capacity of myocytes; the latter could also account for their significantly limited exercise tolerance. [source]

    Effects of phlebotomy on haemodynamic characteristics during exercise in Standardbred trotters with red cell hypervolaemia

    EQUINE VETERINARY JOURNAL, Issue 4 2001
    P. FUNKQUIST
    Summary Five Standardbred trotters with red cell hypervolaemia (RCHV) were compared before and after removal of approximately 22% (36 ml/kg bwt) of the total blood volume in order to evaluate the haemodynamic responses, haemorheological alterations and oxygen transport during exercise to fatigue. Data were recorded during submaximal exercise at 4 different speeds on a treadmill and then during continued running at the highest speed step until fatigue. Oxygen uptake (V,O2), pulmonary artery pressure (PAP), systemic artery pressure (SAP), heart rate (HR), haematocrit and haemoglobin concentrations (Hb) were measured. Arteriovenous O2 content difference (C(a-v,)O2), pulmonary vascular resistance (PVR) and total systemic resistance (TSR) were calculated. Whole blood and plasma viscosity and erythrocyte aggregation tendency were determined with a rotational viscometer. Endoscopy was performed after exercise. ANOVA was used for statistical analysis. Phlebotomy resulted in a decrease in haematocrit and Hb during the course of exercise. Blood and plasma viscosity were lower and erythrocyte aggregation tendency was higher after phlebotomy. Throughout exercise, including submaximal work and continued running to fatigue, PAP, SAP, PVR, TSR and C(a-v,)O2 were lower after phlebotomy. HR was higher after phlebotomy during submaximal exercise. Oxygen delivery and VO2 were lower after phlebotomy in the period from submaximal exercise to fatigue. Run time to fatigue was shorter after phlebotomy. Four horses showed exercise-induced pulmonary haemorrhage (EIPH) before phlebotomy and the degree of bleeding was diminished but not abolished after phlebotomy. The reductions in PVR, TSR, PAP and SAP after phlebotomy were probably a result of reduced blood viscosity. In conclusion, although a 22% reduction in blood volume improved the haemodynamic and haemorheological parameters and the degree of EIPH, it was found that RCHV trotters have to rely on high oxygen delivery to the working muscles for maintenance of maximal performance. [source]

    Reduced oxygen concentration improves the developmental competence of mouse oocytes following in vitro maturation

    MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 7 2007
    Kimberly A. Preis
    Abstract Reduced atmospheric oxygen concentration is beneficial to embryo development; however, optimal oxygen concentration for oocyte maturation remains undetermined. Likewise, there is no consensus of appropriate medium supplementation during maturation. The objective of this study was to determine whether oxygen tension (20% or 5% O2) and epidermal growth factor (EGF) affect oocyte metabolism and subsequent embryo development. Cumulus-oocyte complexes (COCs) were collected from 28-day-old equine chorionic gonadotropin (eCG) primed or unprimed F1 (C57BL/6xCBA) mice. COCs were matured in defined medium in one of four groups: 20% O2, 20% O2,+,EGF, 5% O2, 5% O2,+,EGF. In vivo matured COCs were also collected for analysis. COCs from unprimed mice, matured in 5% O2,±,EGF or 20% O2,+,EGF had higher metabolic rates than COCs matured in 20% O2 (P,<,0.05). COCs from primed mice had higher metabolic rates when matured in the presence of EGF, regardless of oxygen tension (P,<,0.01). Oxygen uptake and mitochondrial membrane potential were higher for in vivo matured oocytes and oocytes matured under 5% O2 compared to oocytes matured under 20% O2 (P,<,0.05). Blastocyst formation was not different between maturation groups (primed or unprimed); however, embryo cell numbers were 20,45% significantly higher when COCs were matured at 5% O2 (P,<,0.05). Results suggest that oocytes matured in physiological concentrations of oxygen have improved development and metabolic activity, more closely resembling in vivo maturation. These findings have implications for oocyte maturation in both clinical and research laboratories. Mol. Reprod. Dev. 74: 893,903, 2007. © 2006 Wiley-Liss, Inc. [source]

    Action of Celecoxib on Hepatic Metabolic Changes Induced by the Walker-256 Tumour in Rats

    BASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 5 2007
    Alexandra Acco
    Celecoxib was administered daily (5,50 mg/kg body weight) beginning at the day in which the tumour cells were inocculated. At day 14, the liver was isolated and perfused in order to measure alanine transformation, glycolysis and arginine transformation. Maximal reduction of tumour growth (75%), accompanied by an almost normal weight gain, was attained with a celecoxib dose of 12.5 mg/kg. Diminution of glucose utilization (glycolysis) and inhibition of gluconeogenesis and ureogenesis from alanine caused by the tumor were totally reversed by celecoxib. Oxygen uptake by the liver was also normalized by the drug. Hepatic arginine transformation, which is normally enhanced in rats bearing the Walker-256 tumour, remained elevated in celecoxib-treated animals. It was concluded that preservation of gluconeogenesis and normalization of hepatic glucose utilization can explain, partly at least, the clinical improvement of cancer patients treated with the drug. The lack of action of celecoxib on arginine hydrolysis might indicate that reduction in polyamine synthesis is not a factor contributing to the diminished tumour growth. [source]

    The validity of the Computer Science and Applications activity monitor for use in coronary artery disease patients during level walking

    CLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 4 2002
    Ulf Ekelund
    Summary The principal aim of the present study was to examine the validity of the Computer Science and Applications (CSA) activity monitor during level walking in coronary artery disease (CAD) patients. As a secondary aim, we evaluated the usefulness of two previously published energy expenditure (EE) prediction equations. Thirty-four subjects (29 men and five women), all with diagnosed CAD, volunteered to participate. Oxygen uptake (VO2) was measured by indirect calorimetry during walking on a motorized treadmill at three different speeds (3·2, 4·8 and 6·4 km h,1). Physical activity was measured simultaneously using the CSA activity monitor, secured directly to the skin on the lower back (i.e. lumbar vertebrae 4,5) with an elastic belt. The mean (±SD) activity counts were 1208 ± 429, 3258 ± 753 and 5351 ± 876 counts min,1, at the three speeds, respectively (P<0·001). Activity counts were significantly correlated to speed (r=0·92; P<0·001), VO2 (ml kg,1 min,1; r=0·87; P<0·001) and EE (kcal min,1; r=0·85, P<0·001). A stepwise linear regression analysis showed that activity counts and body weight together explained 75% of the variation in EE. Predicted EE from previously published equations differed significantly when used in this group of CAD patients. In conclusion, the CSA activity monitor is a valid instrument for assessing the intensity of physical activity during treadmill walking in CAD patients. Energy expenditure can be predicted from body weight and activity counts. [source]

    Disparity in regional and systemic circulatory capacities: do they affect the regulation of the circulation?

    ACTA PHYSIOLOGICA, Issue 4 2010
    J. A. L. Calbet
    Abstract In this review we integrate ideas about regional and systemic circulatory capacities and the balance between skeletal muscle blood flow and cardiac output during heavy exercise in humans. In the first part of the review we discuss issues related to the pumping capacity of the heart and the vasodilator capacity of skeletal muscle. The issue is that skeletal muscle has a vast capacity to vasodilate during exercise [,300 mL (100 g),1 min,1], but the pumping capacity of the human heart is limited to 20,25 L min,1 in untrained subjects and ,35 L min,1 in elite endurance athletes. This means that when more than 7,10 kg of muscle is active during heavy exercise, perfusion of the contracting muscles must be limited or mean arterial pressure will fall. In the second part of the review we emphasize that there is an interplay between sympathetic vasoconstriction and metabolic vasodilation that limits blood flow to contracting muscles to maintain mean arterial pressure. Vasoconstriction in larger vessels continues while constriction in smaller vessels is blunted permitting total muscle blood flow to be limited but distributed more optimally. This interplay between sympathetic constriction and metabolic dilation during heavy whole-body exercise is likely responsible for the very high levels of oxygen extraction seen in contracting skeletal muscle. It also explains why infusing vasodilators in the contracting muscles does not increase oxygen uptake in the muscle. Finally, when ,80% of cardiac output is directed towards contracting skeletal muscle modest vasoconstriction in the active muscles can evoke marked changes in arterial pressure. [source]

    Mechanisms of exercise-induced improvements in the contractile apparatus of the mammalian myocardium

    ACTA PHYSIOLOGICA, Issue 4 2010
    O. J. Kemi
    Abstract One of the main outcomes of aerobic endurance exercise training is the improved maximal oxygen uptake, and this is pivotal to the improved work capacity that follows the exercise training. Improved maximal oxygen uptake in turn is at least partly achieved because exercise training increases the ability of the myocardium to produce a greater cardiac output. In healthy subjects, this has been demonstrated repeatedly over many decades. It has recently emerged that this scenario may also be true under conditions of an initial myocardial dysfunction. For instance, myocardial improvements may still be observed after exercise training in post-myocardial infarction heart failure. In both health and disease, it is the changes that occur in the individual cardiomyocytes with respect to their ability to contract that by and large drive the exercise training-induced adaptation to the heart. Here, we review the evidence and the mechanisms by which exercise training induces beneficial changes in the mammalian myocardium, as obtained by means of experimental and clinical studies, and argue that these changes ultimately alter the function of the whole heart and contribute to the changes in whole-body function. [source]

    Cerebral oxygenation is reduced during hyperthermic exercise in humans

    ACTA PHYSIOLOGICA, Issue 1 2010
    P. Rasmussen
    Abstract Aim:, Cerebral mitochondrial oxygen tension (PmitoO2) is elevated during moderate exercise, while it is reduced when exercise becomes strenuous, reflecting an elevated cerebral metabolic rate for oxygen (CMRO2) combined with hyperventilation-induced attenuation of cerebral blood flow (CBF). Heat stress challenges exercise capacity as expressed by increased rating of perceived exertion (RPE). Methods:, This study evaluated the effect of heat stress during exercise on PmitoO2 calculated based on a Kety-Schmidt-determined CBF and the arterial-to-jugular venous oxygen differences in eight males [27 ± 6 years (mean ± SD) and maximal oxygen uptake (VO2max) 63 ± 6 mL kg,1 min,1]. Results:, The CBF, CMRO2 and PmitoO2 remained stable during 1 h of moderate cycling (170 ± 11 W, ,50% of VO2max, RPE 9,12) in normothermia (core temperature of 37.8 ± 0.4 °C). In contrast, when hyperthermia was provoked by dressing the subjects in watertight clothing during exercise (core temperature 39.5 ± 0.2 °C), PmitoO2 declined by 4.8 ± 3.8 mmHg (P < 0.05 compared to normothermia) because CMRO2 increased by 8 ± 7% at the same time as CBF was reduced by 15 ± 13% (P < 0.05). During exercise with heat stress, RPE increased to 19 (19,20; P < 0.05); the RPE correlated inversely with PmitoO2 (r2 = 0.42, P < 0.05). Conclusion:, These data indicate that strenuous exercise in the heat lowers cerebral PmitoO2, and that exercise capacity in this condition may be dependent on maintained cerebral oxygenation. [source]

    Impact of carbohydrate supplementation during endurance training on glycogen storage and performance

    ACTA PHYSIOLOGICA, Issue 2 2009
    L. Nybo
    Abstract Aim:, Glucose ingestion may improve exercise endurance, but it apparently also influences the transcription rate of several metabolic genes and it alters muscle metabolism during an acute exercise bout. Therefore, we investigated how chronic training responses are affected by glucose ingestion. Methods:, In previously untrained males performance and various muscular adaptations were evaluated before and after 8 weeks of supervised endurance training conducted either with (n = 8; CHO group) or without (n = 7; placebo) glucose supplementation. Results:, The two groups achieved similar improvements in maximal oxygen uptake and peak power output during incremental cycling (both parameters elevated by 17% on average) and both groups lost ,3 kg of fat mass during the 8 weeks of training. An equal reduction in respiratory exchange ratio (0.02 units) during submaximal exercise was observed in both groups. Beta-hydroxyacyl-CoA-dehydrogenase activity was increased in both groups, however, to a larger extent in the placebo group (45 ± 11%) than CHO (23 ± 9%, P < 0.05). GLUT-4 protein expression increased by 74 ± 14% in the placebo group and 45 ± 14% in CHO (both P < 0.05), while resting muscle glycogen increased (P < 0.05) to a larger extent in the placebo group (96 ± 4%) than CHO (33 ± 2%). Conclusion:, These results show that carbohydrate supplementation consumed during exercise training influences various muscular training adaptations, but improvements in cardiorespiratory fitness and reductions in fat mass are not affected. [source]

    Circulatory effects of apnoea in elite breath-hold divers

    ACTA PHYSIOLOGICA, Issue 1 2009
    F. Joulia
    Abstract Aim:, Voluntary apnoea induces several physiological adaptations, including bradycardia, arterial hypertension and redistribution of regional blood flows. Elite breath-hold divers (BHDs) are able to maintain very long apnoea, inducing severe hypoxaemia without brain injury or black-out. It has thus been hypothesized that they develop protection mechanisms against hypoxia, as well as a decrease in overall oxygen uptake. Methods:, To test this hypothesis, the apnoea response was studied in BHDs and non-divers (NDs) during static and dynamic apnoeas (SA, DA). Heart rate, arterial oxygen saturation (SaO2), and popliteal artery blood flow were recorded to investigate the oxygen-conserving effect of apnoea response, and the internal carotid artery blood flow was used to examine the mechanisms of cerebral protection. Results:, The bradycardia and peripheral vasoconstriction were accentuated in BHDs compared with NDs (P < 0.01), in association with a smaller SaO2 decrease (,2.7% vs. ,4.9% during SA, P < 0.01 and ,6% vs. ,11.3% during DA, P < 0.01). Greater increase in carotid artery blood flow was also measured during apnoea in BHDs than in controls. Conclusion:, These results confirm that elite divers present a potentiation of the well-known apnoea response in both SA and DA conditions. This response is associated with higher brain perfusion which may partly explain the high levels of world apnoea records. [source]

    Non-invasive measurements of the mean alveolar O2 tension from the oxygen uptake versus tidal volume curve

    ACTA PHYSIOLOGICA, Issue 2 2007
    Hans Malte
    No abstract is available for this article. [source]

    Lifestyle, participation, and health-related quality of life in adolescents and young adults with myelomeningocele

    DEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 11 2009
    LAURIEN M BUFFART PHD
    This study aimed to describe participation and health-related quality of life (HRQoL) in adolescents and young adults with myelomeningocele and to explore their relationships with lifestyle-related factors. Fifty-one individuals with a mean age of 21 years 1 month (SD 4y 6mo) years participated (26 males, 25 females; 82% hydrocephalus, 55% wheelchair-dependent). Participation was assessed using the Life Habits Questionnaire, and HRQoL was assessed using the Medical Outcomes Study 36-item Short-form Health Survey. Physical activity was measured using an accelerometry-based activity monitor, fitness (peak oxygen uptake) was measured during a maximal exercise test, and the sum of four skin-folds was assessed to indicate body fat. Relationships were studied using logistic regression analyses. Of the participants, 63% had difficulties in daily activities and 59% in social roles. Participants perceived lower physical HRQoL than a Dutch reference population. Participants with higher levels of physical activity and fitness had fewer difficulties in participating in daily activities (odds ratio [OR]=8.8, p=0.02 and OR=29.7, p=0.02 respectively) and a higher physical HRQoL (OR=4.8, p=0.02 and OR=30.2, p=0.006 respectively), but not mental HRQoL. Body fat was not related to participation or HRQoL. In conclusion, a large proportion of individuals with myelomeningocele had difficulties in participation and perceived low physical HRQoL. Higher levels of physical activity and fitness were related to fewer difficulties in participation and higher physical HRQoL. [source]

    Exercise-induced growth hormone response in euglycaemia and hyperglycaemia in patients with Type 1 diabetes mellitus

    DIABETIC MEDICINE, Issue 2 2010
    S. Jenni
    Diabet. Med. 27, 230,233 (2010) Abstract Aims, To compare exercise-induced growth hormone (GH) response in patients with Type 1 diabetes during stable euglycaemic and hyperglycaemic conditions. Methods, We conducted a randomized, controlled, single-blinded cross-over trial in seven male patients with well-controlled Type 1 diabetes. The patients cycled twice for 120 min at a level of 55,60% maximal oxygen uptake. Euglycaemia was at 5.0 mmol/l, hyperglycaemia at 11.0 mmol/l. Results, Area under the curve of GH (AUCGH) during exercise was significantly higher during euglycaemia [1430 ng ml,1 min, 95% confidence interval (CI) 703,2910] compared with hyperglycaemia (1061 ng ml,1 min, 95% CI 538,2091, P = 0.02). Conclusions, In patients with Type 1 diabetes, GH concentrations during moderate aerobic exercise during stable hyperglycaemic conditions are significantly lower compared with euglycaemia. These findings are compatible with preserved glucose-mediated GH regulation during exercise in individuals with well-controlled Type 1 diabetes. [source]

    Does aerobic fitness influence microvascular function in healthy adults at risk of developing Type 2 diabetes?

    DIABETIC MEDICINE, Issue 4 2005
    A. R. Middlebrooke
    Abstract Aim To investigate whether aerobic fitness is associated with skin microvascular function in healthy adults with an increased risk of developing Type 2 diabetes. Methods Twenty-seven healthy normal glucose-tolerant humans with either a previous diagnosis of gestational diabetes or having two parents with Type 2 diabetes and 27 healthy adults who had no history of diabetes were recruited. Maximal oxygen uptake was assessed using an incremental exercise test to exhaustion. Skin microvascular function was assessed using laser Doppler techniques as the maximum skin hyperaemic response to a thermal stimulus (maximum hyperaemia) and the forearm skin blood flow response to the iontophoretic application of acetylcholine (ACh) and sodium nitroprusside. Results Maximal oxygen uptake was not significantly different in the ,at-risk' group compared with healthy controls. Maximum hyperaemia was reduced in those ,at risk' (1.29 ± 0.30 vs. 1.46 ± 0.33 V, P = 0.047); however, the peak response to acetylcholine or sodium nitroprusside did not differ in the two groups. A significant positive correlation was demonstrated between maximal oxygen uptake and maximum hyperaemia (r = 0.52, P = 0.006 l/min and r = 0.60, P = 0.001 ml/kg/min) and peak ACh response (r = 0.40, P = 0.04 l/min and r = 0.47, P = 0.013 ml/kg/min) in the ,at-risk' group when expressed in absolute (l/min) or body mass-related (ml/kg/min) terms. No significant correlations were found in the control group. Conclusions In this ,at-risk' group with skin microvascular dysfunction maximal oxygen uptake was not reduced compared with healthy controls. However, in the ,at-risk' group alone, individuals with higher levels of aerobic fitness also had better microvascular and endothelial responsiveness. [source]

    Effects of a new 1,3,4-thiadiazolium mesoionic compound, MI-D, on the acute inflammatory response

    DRUG DEVELOPMENT RESEARCH, Issue 4 2004
    Júlio C. Cardoso
    Abstract A new mesoionic compound, 4-phenyl-5-(4-nitro-cinnamoyl)-1,3,4-thiadiazolium-2-phenylamine (MI-D), is described along with some of its biological properties. Its effects on hepatic metabolism, on O and nitric oxide (NO) production, and in in vivo models for potential antinociceptive, antipyretic, and antiinflammatory activities were determined. In perfused rat liver, MI-D (25 µM) stimulated glycogenolysis (95%), and inhibited oxygen uptake (37%) with affecting glycolysis. In phorbol 12-myristate 13-acetate-stimulated macrophages, O generation was reduced (95%) by MI-D (15 µM), whereas the production of NO was unaffected. MI-D (2 mg/kg) inhibited (55%) the number of abdominal writhings induced by acetic acid. At 1 mg/kg, MI-D inhibited the febrile response (5 h) induced by lipopolysaccharide (LPS) and was also effective against a preexisting febrile response. Treatment with MI-D (1 mg/kg) reduced by 67% prostaglandin (PGE2) levels in the cerebrospinal fluid of LPS-exposed mice, and at a higher dose (8 mg/kg) MI-D inhibited paw edema formation (2 h) induced by carrageenan. MI-D has a spectrum of activities similar to other nonsteroidal antiinflammatory drugs, qualifying it as a potential anti-inflammatory drug. Drug Dev. Res. 61:207,217, 2004. © 2004 Wiley-Liss, Inc. [source]

    In situ substrate conversion and assimilation by nitrifying bacteria in a model biofilm

    ENVIRONMENTAL MICROBIOLOGY, Issue 9 2005
    Armin Gieseke
    Summary Local nitrification and carbon assimilation activities were studied in situ in a model biofilm to investigate carbon yields and contribution of distinct populations to these activities. Immobilized microcolonies (related to Nitrosomonas europaea/eutropha, Nitrosomonas oligotropha, Nitrospira sp., and to other Bacteria) were incubated with [14C]-bicarbonate under different experimental conditions. Nitrifying activity was measured concomitantly with microsensors (oxygen, ammonium, nitrite, nitrate). Biofilm thin sections were subjected to fluorescence in situ hybridization (FISH), microautoradiography (MAR), and local quantification of [14C]-bicarbonate uptake (beta microimaging). Nitrifying activity and tracer assimilation were restricted to a surface layer of different thickness in the various experiments (substrate or oxygen limitation). Excess oxygen uptake under all conditions revealed heterotrophic activity fuelled by decay or excretion products during active nitrification. Depth limits and intensity of tracer incorporation profiles were in agreement with ammonia-oxidation activity (measured with microsensors), and distribution of incorporated tracer (detected with MAR). Microautoradiography revealed a sharp individual response of distinct populations in terms of in-/activity depending on the (local) environmental conditions within the biofilm. Net in situ carbon yields on N, expressed as e, equivalent ratios, varied between 0.005 and 0.018, and, thus, were in the lower range of data reported for pure cultures of nitrifiers. [source]

    Differential inhibition in vivo of ammonia monooxygenase, soluble methane monooxygenase and membrane-associated methane monooxygenase by phenylacetylene

    ENVIRONMENTAL MICROBIOLOGY, Issue 5 2000
    Sonny Lontoh
    Phenylacetylene was investigated as a differential inhibitor of ammonia monooxygenase (AMO), soluble methane monooxygenase (sMMO) and membrane-associated or particulate methane monooxygenase (pMMO) in vivo. At phenylacetylene concentrations >,1 µM, whole-cell AMO activity in Nitrosomonas europaea was completely inhibited. Phenylacetylene concentrations above 100 µM inhibited more than 90% of sMMO activity in Methylococcus capsulatus Bath and Methylosinus trichosporium OB3b. In contrast, activity of pMMO in M. trichosporium OB3b, M. capsulatus Bath, Methylomicrobium album BG8, Methylobacter marinus A45 and Methylomonas strain MN was still measurable at phenylacetylene concentrations up to 1000 µM. AMO of Nitrosococcus oceanus has more sequence similarity to pMMO than to AMO of N. europaea. Correspondingly, AMO in N. oceanus was also measurable in the presence of 1000 µM phenylacetylene. Measurement of oxygen uptake indicated that phenylacetylene acted as a specific and mechanistic-based inhibitor of whole-cell sMMO activity; inactivation of sMMO was irreversible, time dependent, first order and required catalytic turnover. Corresponding measurement of oxygen uptake in whole cells of methanotrophs expressing pMMO showed that pMMO activity was inhibited by phenylacetylene, but only if methane was already being oxidized, and then only at much higher concentrations of phenylacetylene and at lower rates compared with sMMO. As phenylacetylene has a high solubility and low volatility, it may prove to be useful for monitoring methanotrophic and nitrifying activity as well as identifying the form of MMO predominantly expressed in situ. [source]

    Toxicity assessment of mono-substituted benzenes and phenols using a Pseudomonas initial oxygen uptake assay

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2005
    Ded-Shih Huang
    Abstract A methodology is presented for assessing the toxicity of chemical substances through their inhibitory action toward the Pseudomonas initial oxygen uptake (PIOU) rate. The current studies reveal that the PIOU assay is rapid, cost-efficient, and easy to perform. The oxygen uptake rate was found to be associated with a putative benzoate transporter and highly dependent on benzoate concentration. The putative benzoate transporter has been shown to follow Michaelis,Menten kinetics. Most phenols were found to be noncompetitive inhibitors of the benzoate transporter. The inhibition constant (Ki) of these noncompetitive inhibitors can be related to the concentration causing 50% oxygen uptake inhibition in Pseudomonas putida. Modeling these data by using the response,surface approach leads to the development of a quantitative structure,activity relationship (QSAR) for the toxicity of phenols ((1/Ki) = ,0.435 (±0.038) lowest-unoccupied-molecular orbital + 0.517 (±0.027)log KOW ,2.340 (±0.068), n = 49, r2 = 0.930, s = 0.107, r2adj = 0.926, F = 303.1). A comparison of QSAR models derived from the Ki data of the PIOU method and the toxicity data of 40-h Tetrahymena pyrifomis growth inhibition assay (Tetratox) indicated that there was a high correlation between the two approaches (r2 = 0.925). [source]

    Endothelial markers in chronic heart failure: training normalizes exercise-induced vWF release

    EUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 9 2004
    L. W. E. Sabelis
    Abstract Background, Chronic heart failure (CHF) is characterized by endothelial dysfunction. Vascular endothelium is important for control of haemostasis and vasoregulation. The aim of the present study was to investigate plasma levels of several endothelial markers and the exercise-induced changes on these plasma levels in CHF patients. Subsequently, the effect of a 6-month training programme on these markers is described. Materials and methods, Twenty-nine male CHF patients (NYHA II/III, age 60 ± 8 year, body mass index 26·7 ± 2·3 kg m,2, left ventricular ejection fraction 26·3,7·2%; mean ± SD) participated. Patients were randomly assigned to a training or control group. Training (26 weeks; combined strength and endurance exercises) was four sessions/week: two sessions supervised and two sessions at home. Before and after intervention, anthropometry, endothelial markers (haemostasis and vasoregulation), maximal workload and peak oxygen uptake were assessed. Results, Physical training positively affected maximal workload. Plasma levels of endothelial markers were not affected by physical training and not related to exercise tolerance. After training, stimulated (maximal exercise) plasma von Willebrand Factor (vWF) release was present, whereas at baseline this release was absent. Conclusion, Physical training led to normalization of the stimulated plasma vWF release. Plasma levels of other endothelial markers were not affected by physical training either at rest or under stimulated (maximal exercise) conditions. [source]

    The training stimulus experienced by the leg muscles during cycling in humans

    EXPERIMENTAL PHYSIOLOGY, Issue 6 2009
    Jamie S. McPhee
    Considerable variability exists between people in their health- and performance-related adaptations to conventional endurance training. We hypothesized that some of this variability might be due to differences in the training stimulus received by the working muscles. In 71 young sedentary women we observed large variations in the ratio of one-leg cycling muscle aerobic capacity to two-leg cycling whole-body maximal oxygen uptake (; Ratio1:2; range 0.58,0.96). The variability in Ratio1:2 was primarily due to differences between people in one-leg (r= 0.71, P < 0.0005) and was not related to two-leg (r= 0.15, P= 0.209). Magnetic resonance imaging (n= 30) and muscle biopsy sampling (n= 20) revealed that one-leg was mainly determined by muscle volume (r= 0.73, P < 0.0005) rather than muscle fibre type or oxidative capacity. A high one-leg was associated with favourable lipoprotein profiles (P= 0.033, n= 24) but this was not the case for two-leg . Calculations based on these data suggest that conventional two-leg exercise at 70% requires subjects with the lowest Ratio1:2 to work their legs at 60% of single-leg , whilst those with the highest Ratio1:2 work their legs at only 36% of maximum. It was concluded that endurance training carried out according to current guidelines will result in highly variable training stimuli for the leg muscles and variable magnitudes of adaptation. These conclusions have implications for the prescription of exercise to improve health and for investigations into the genetic basis of muscle adaptations. [source]

    Nitric oxide synthase inhibition reduces O2 cost of force development and spares high-energy phosphates following contractions in pump-perfused rat hindlimb muscles

    EXPERIMENTAL PHYSIOLOGY, Issue 3 2006
    David J. Baker
    The purpose of the present experiments was to test the hypotheses that: (i) nitric oxide synthase (NOS) inhibition reduces the O2 cost of force development across a range of contractile demands; and (ii) this reduced O2 cost of force development would be reflected in a sparing of intramuscular higher energy phosphates. Rat distal hindlimb muscles were pump perfused in situ and electrically stimulated (200 ms trains with pulses at 100 Hz, each pulse 0.05 ms duration) for 1 min each at 15, 30 and 60 tetani min,1 and for 2 min at 90 tetani min,1 in three groups: 0.01 mm adenosine; 1 mm d -NAME and 0.01 mm adenosine (d -NAME); and 1 mm l -NAME and 0.01 mm adenosine (l -NAME). The gastrocnemius,plantaris,soleus muscle group was freeze clamped post-contractions for metabolite analyses. Force was 19% higher and oxygen uptake was 20% lower with l -NAME versus adenosine, and there was a 35% reduction in /time-integrated tension versus adenosine and 24% versusd -NAME that was independent of contraction frequency. l -NAME treatment produced a 33% sparing of muscle phosphocreatine (PCr), and intramuscular lactate was no different between groups. In contrast, d -NAME reduced force by 30%, by 29% and the O2 cost of force development by 15% compared with adenosine, but had no effect on the degree of intramuscular ATP and PCr depletion. These results show that NOS inhibition improved the metabolic efficiency of force development, either by improving the ATP yield for a given O2 consumption or by reducing the ATP cost of force development. In addition, these effects were independent of contraction frequency. [source]

    Modelling the Influence of Age, Body Size and Sex on Maximum Oxygen Uptake in Older Humans

    EXPERIMENTAL PHYSIOLOGY, Issue 2 2000
    Patrick J. Johnson
    The purpose of this study was to describe the influence of body size and sex on the decline in maximum oxygen uptake (V,O2,max) in older men and women. A stratified random sample of 152 men and 146 women, aged 55-86 years, was drawn from the study population. Influence of age on V,O2,max, independent of differences in body mass (BM) or fat-free mass (FFM), was investigated using the following allometric model: V,O2,max= BMb (or FFMb) exp(a + (c × age) + (d × sex)) [epsilon]. The model was linearised and parameters identified using standard multiple regression. The BM model explained 68.8% of the variance in V,O2,max. The parameters (± s.e.e., standard error of the estimate) for lnBM (0.563 ± 0.070), age (-0.0154 ± 0.0012), sex (0.242 ± 0.024) and the intercept (-1.09 ± 0.32) were all significant (P < 0.001). The FFM model explained 69.3% of the variance in V,O2,max, and the parameters (± s.e.e) lnFFM (0.772 ± 0.090), age (-0.0159 ± 0.0012) and the intercept (-1.57 ± 0.36) were significant (P < 0.001), while sex (0.077 +/, 0.038) was significant at P = 0.0497. Regardless of the model used, the age-associated decline was similar, with a relative decline of 15% per decade (0.984 exp(age)) in V,O2,max in older humans being estimated. The study has demonstrated that, for a randomly drawn sample, the age-related loss in V,O2,max is determined, in part, by the loss of fat-free body mass. When this factor is accounted for, the loss of V,O2,max across age is similar in older men and women. [source]

    Aspergillus oryzae in solid-state and submerged fermentations

    FEMS YEAST RESEARCH, Issue 2 2002
    Progress report on a multi-disciplinary project
    Abstract We report the progress of a multi-disciplinary research project on solid-state fermentation (SSF) of the filamentous fungus Aspergillus oryzae. The molecular and physiological aspects of the fungus in submerged fermentation (SmF) and SSF are compared and we observe a number of differences correlated with the different growth conditions. First, the aerial hyphae which occur only in SSFs are mainly responsible for oxygen uptake. Second, SSF is characterised by gradients in temperature, water activity and nutrient concentration, and inside the hyphae different polyols are accumulating. Third, pelleted growth in SmF and mycelial growth in SSF show different gene expression and protein secretion patterns. With this approach we aim to expand our knowledge of mechanisms of fungal growth on solid substrates and to exploit the biotechnological applications. [source]

    A Study to Evaluate the Feasibility of an Aerobic Exercise Program in Patients With Migraine

    HEADACHE, Issue 4 2009
    Emma Varkey RPT
    Objectives., The aim of this study was to develop and evaluate an exercise program to improve maximum oxygen uptake (VO2 max) in untrained patients with migraine without making their migraines worse. Patients and methods., Twenty-six patients were studied at a headache clinic in Sweden. The exercise program, based on indoor cycling, was performed 3 times per week during 12 weeks. VO2 max, migraine status, side effects, and quality of life were evaluated. Results., VO2 max increased from 32.9 mL/kg/minute to 36.2 mL/kg/minute (P = .044). Quality of life increased and significant improvements in migraine status (attack frequency, symptom intensity, and intake of medicine) were seen. During the 12 weeks of exercise, on one occasion one patient had a migraine attack, which started immediately after training. No other side effects were reported. Conclusions., The evaluated exercise program was well tolerated by the patients and improved their VO2 max with no deterioration of migraine status. [source]

    Effect of Campsurus notatus on NH+4, DOC Fluxes, O2 Uptake and Bacterioplankton Production in Experimental Microcosms with Sediment-Water Interface of an Amazonian Lake Impacted by Bauxite Tailings

    INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 2 2003
    João José Fonseca Leal
    Abstract The aim of this study was to evaluate the influence of Campusurus notatusEaton 1868 (Ephemeroptera: Polimitarciydae) and the impact of bauxite tailings on ammonium (NH4+) and dissolved organic carbon (DOC) fluxes, oxygen uptake and bacterioplankton production in the sediment-water interface of Lake Batata, a shallow Amazonian floodplain lake. Mesocosms were constructed from natural and impacted areas of Lake Batata, to reproduce the sediment-water interface. The cores were incubated with 0 to 2,388 ind m,2 of Campsurus notatus nymphs, and the changes in NH4+, DOC, O2 concentration and bacterioplankton production in the overlying water column were measured. Ammonium efflux (F = 9.8, p < 0.05, multiple regression) and oxygen uptake (F = 11.8, p < 0.05) showed a significant correlation with the density of C. notatus in the cores with natural sediment. No differences on DOC release were observed in cores with natural or impacted sediment. In the cores incubated with natural sediment and nymphs of C. notatus, a significant increase (Two-way ANOVA, p < 0.05) in bacterial production (0.44 ,g C l,1 h,1) was observed after 3 hours of incubation. In cores incubated with sediment impacted by bauxite tailings, there was no difference in bacterial production with and without C. notatus. We conclude that C. notatus is an important bioturbator in Lake Batata, increasing the turnover rate of nitrogen (NH4+) at the sediment-water interface and bacterial production in cores incubated with natural sediment. It is also clear that bauxite tailings reduce the nutrients turnover rates in impacted regions of Lake Batata and influence bacterial production. [source]

    Cardiovascular Exercise Training Extends Influenza Vaccine Seroprotection in Sedentary Older Adults: The Immune Function Intervention Trial

    JOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 12 2009
    Jeffrey A. Woods PhD
    OBJECTIVES: To determine whether cardiovascular exercise training resulted in improved antibody responses to influenza vaccination in sedentary elderly people who exhibited poor vaccine responses. DESIGN: Single-site randomized parallel-arm 10-month controlled trial. SETTING: University of Illinois at Urbana-Champaign. PARTICIPANTS: One hundred forty-four sedentary, healthy older (69.9 ± 0.4) adults. INTERVENTIONS: Moderate (60,70% maximal oxygen uptake) cardiovascular exercise was compared with flexibility and balance training. MEASUREMENTS: The primary outcome was influenza vaccine response, as measured according to hemagglutination inhibition (HI) anti-influenza antibody titer and seroprotective responses (HI titer ,40). Secondary measures included cardiovascular fitness and body composition. RESULTS: Of the 160 participants enrolled, 144 (90%) completed the 10-month intervention with excellent compliance (,83%). Cardiovascular, but not flexibility, exercise intervention resulted in improvements in indices of cardiovascular fitness, including maximal oxygen uptake. Although not affecting peak (e.g., 3 and 6 weeks) postvaccine anti-influenza HI titers, cardiovascular exercise resulted in a significant increase in seroprotection 24 weeks after vaccination (30,100% dependent on vaccine variant), whereas flexibility training did not. CONCLUSION: Participants randomized to cardiovascular exercise experienced improvements in influenza seroprotection throughout the entire influenza season, whereas those in the balance and flexibility intervention did not. Although there were no differences in reported respiratory tract infections, the exercise group exhibited reduced overall illness severity and sleep disturbance. These data support the hypothesis that regular endurance exercise improves influenza vaccine responses. [source]

    Temperature-dependent changes in energy metabolism, intracellular pH and blood oxygen tension in the Atlantic cod

    JOURNAL OF FISH BIOLOGY, Issue 6 2003
    F. J. Sartoris
    The effect of acute increase in temperature on oxygen partial pressure (Po2) was measured in the gill arches of Atlantic cod Gadus morhua between 10 and 19° C by use of oxygen microoptodes. Oxygen saturation of the gill blood under control conditions varied between 90 and 15% reflecting a variable percentage of arterial or venous blood in accordance with the position of each optode in the gill arch. The data obtained suggested that arterial Po2 remained more or less constant and arterial oxygen uptake did not become limiting during warming. A progressive drop in venous Po2, however, was observed at >10° C indicating that excessive oxygen uptake from the blood is not fully compensated for by circulatory performance, until finally, Po2 levels fully collapse. In a second set of experiments energy and acid,base status of white muscle of Atlantic cod in vivo was measured by magnetic resonance (31P-NMR) spectroscopy in unanaesthetized and unimmobilized fish in the temperature range between 13 and 21° C. A decrease in white muscle intracellular pH (pHi) with temperature occurred between 10 and 16° C (,pH per ° C = ,0·025 per ° C). In white muscle temperature changes had no influence on high-energy phosphates such as phosphocreatine (PCr) or ATP except during exposure to high critical temperatures (>16° C), indicating that white muscle energy status appears to be relatively insensitive to thermal stress if compared to the thermal sensitivity of the whole animal. The data were consistent with the hypothesis of an oxygen limitation of thermal tolerance in animals, which is set by limited capacity of oxygen supply mechanisms. In the case of Atlantic cod circulatory rather than ventilatory performance may be the first process to cause oxygen deficiency during heat stress. [source]

    Chronic fatigue syndrome: assessment of increased oxidative stress and altered muscle excitability in response to incremental exercise

    JOURNAL OF INTERNAL MEDICINE, Issue 3 2005
    Y. JAMMES
    Abstract. Objectives., Because the muscle response to incremental exercise is not well documented in patients suffering from chronic fatigue syndrome (CFS), we combined electrophysiological (compound-evoked muscle action potential, M wave), and biochemical (lactic acid production, oxidative stress) measurements to assess any muscle dysfunction in response to a routine cycling exercise. Design., This case,control study compared 15 CFS patients to a gender-, age- and weight-matched control group (n = 11) of healthy subjects. Interventions., All subjects performed an incre-mental cycling exercise continued until exhaustion. Main outcome measures., We measured the oxygen uptake (Vo2), heart rate (HR), systemic blood pressure, percutaneous O2 saturation (SpO2), M-wave recording from vastus lateralis, and venous blood sampling allowing measurements of pH (pHv), PO2 (PvO2), lactic acid (LA), and three markers of the oxidative stress (thiobarbituric acid-reactive substances, TBARS, reduced glutathione, GSH, and ascorbic acid, RAA). Results., Compared with control, in CFS patients (i) the slope of Vo2 versus work load relationship did not differ from control subjects and there was a tendency for an accentuated PvO2 fall at the same exercise intensity, indicating an increased oxygen uptake by the exercising muscles; (ii) the HR and blood pressure responses to exercise did not vary; (iii) the anaerobic pathways were not accentuated; (iv) the exercise-induced oxidative stress was enhanced with early changes in TBARS and RAA and enhanced maximal RAA consumption; and (v) the M-wave duration markedly increased during the recovery period. Conclusions., The response of CFS patients to incremental exercise associates a lengthened and accentuated oxidative stress together with marked alterations of the muscle membrane excitability. These two objective signs of muscle dysfunction are sufficient to explain muscle pain and postexertional malaise reported by our patients. [source]