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Cerebrovascular Diseases (Basel,... 2023The peak oxygen consumption (V.O2peak) and blood hemoglobin concentration [Hb] are lower in stroke patients than in age-matched healthy subjects. The ability of skeletal...
BACKGROUND
The peak oxygen consumption (V.O2peak) and blood hemoglobin concentration [Hb] are lower in stroke patients than in age-matched healthy subjects. The ability of skeletal muscles to extract oxygen is diminished after stroke. We hypothesized that the oxygen extraction capacity of skeletal muscles in stroke patients depends on [Hb]. To test the hypothesis, we determined the relationship between V.O2peak and total hemoglobin mass (tHb-mass) in stroke patients.
METHODS
The subjects were 19 stroke patients (age: 74 ± 2, mean ± SD, 10 males) and 11 age-matched normal subjects (age 76 ± 3, 6 males). Plasma volume (PV) and V.O2peak were measured on the same day. PV was measured using Evans Blue dye dilution method. Blood volume (BV) was calculated from PV and hematocrit, while tHb-mass was estimated from BV and [Hb]. Each subject underwent cardiopulmonary exercise test on a bicycle ergometer using a V.O2peak respiratory gas analyzer.
RESULTS
There were no differences in age, height, and weight between the two groups. V.O2peak was lower in stroke patients than in the control. BV and tHb mass were not significantly different between the two groups, but [Hb] was significantly lower in stroke patients. In stroke patients, V.O2peak correlated significantly with tHb-mass (r = 0.497, p < 0.05), but not with BV.
CONCLUSION
Our results suggested that low [Hb] seems to contribute to V.O2peak in stroke patients. The significant correlation between tHb-mass and V.O2peak suggested that treatment to improve [Hb] can potentially improve V.O2peak in stroke patients.
Topics: Aged; Humans; Male; Exercise Test; Hemoglobins; Oxygen; Oxygen Consumption; Stroke; Female
PubMed: 35917807
DOI: 10.1159/000525597 -
Journal of Applied Physiology... Jul 1997The purpose of this study was to determine whether aerobic fitness level would influence measurements of excess postexercise oxygen consumption (EPOC) and initial rate... (Clinical Trial)
Clinical Trial Comparative Study
The purpose of this study was to determine whether aerobic fitness level would influence measurements of excess postexercise oxygen consumption (EPOC) and initial rate of recovery. Twelve trained [Tr; peak oxygen consumption (VO2 peak) = 53.3 +/- 6.4 ml . kg-1 . min-1] and ten untrained (UT; VO2 peak = 37.4 +/- 3.2 ml . kg-1 . min-1) subjects completed two 30-min cycle ergometer tests on separate days in the morning, after a 12-h fast and an abstinence from vigorous activity of 24 h. Baseline metabolic rate was established during the last 10 min of a 30-min seated preexercise rest period. Exercise workloads were manipulated so that they elicited the same relative, 70% VO2 peak (W70%), or the same absolute, 1.5 l/min oxygen uptake (VO2) (W1.5), intensity for all subjects, respectively. Recovery VO2, heart rate (HR), and respiratory exchange ratio (RER) were monitored in a seated position until baseline VO2 was reestablished. Under both exercise conditions, Tr had shorter EPOC duration (W70% = 40 +/- 15 min, W1.5 = 21 +/- 9 min) than UT (W70% = 50 +/- 14 min; W1.5 = 39 +/- 14 min), but EPOC magnitude (Tr: W70% = 3.2 +/- 1.0 liters O2, W1.5 = 1.5 +/- 0.6 liters O2; UT: W70% = 3.5 +/- 0.9 liters O2, W1.5 = 2.4 +/- 0.6 liters O2) was not different between groups. The similarity of Tr and UT EPOC accumulation in the W70% trial is attributed to the parallel decline in absolute VO2 during most of the initial recovery period. Tr subjects had faster relative decline during the fast-recovery phase, however, when a correction for their higher exercise VO2 was taken. Postexercise VO2 was lower for Tr group for nearly all of the W1.5 trial and particularly during the fast phase. Recovery HR kinetics were remarkably similar for both groups in W70%, but recovery was faster for Tr during W1.5. RER values were at or below baseline throughout much of the recovery period in both groups, with UT experiencing larger changes than Tr in both trials. These findings indicate that Tr individuals have faster regulation of postexercise metabolism when exercising at either the same relative or same absolute work rate.
Topics: Adult; Anaerobic Threshold; Energy Metabolism; Exercise; Exercise Test; Female; Heart Rate; Humans; Male; Oxygen Consumption; Physical Fitness; Ventilation-Perfusion Ratio
PubMed: 9216958
DOI: 10.1152/jappl.1997.83.1.153 -
Thorax Nov 1992
Review
Topics: Critical Illness; Heart; Humans; Lung; Oxygen; Oxygen Consumption; Respiration
PubMed: 1465759
DOI: 10.1136/thx.47.11.971 -
The British Journal of Radiology Jan 2019Tumour hypoxia is a well-recognised barrier to anti-cancer therapy and represents one of the best validated targets in oncology. Previous attempts to tackle hypoxia have... (Review)
Review
Tumour hypoxia is a well-recognised barrier to anti-cancer therapy and represents one of the best validated targets in oncology. Previous attempts to tackle hypoxia have focussed primarily on increasing tumour oxygen supply; however, clinical studies using this approach have yielded only modest clinical benefit, with often significant toxicity and practical limitations. Therefore, there are currently no anti-hypoxia treatments in widespread clinical use. As an emerging alternative strategy, we discuss the relevance of inhibiting tumour oxygen metabolism to alleviate hypoxia and highlight recently initiated clinical trials using this approach.
Topics: Cell Hypoxia; Disease Progression; Drug Delivery Systems; Female; Humans; Male; Needs Assessment; Neoplasm Invasiveness; Nimorazole; Oxygen Consumption; Prognosis; Radiotherapy; Randomized Controlled Trials as Topic; Tumor Burden; Tumor Hypoxia
PubMed: 29436847
DOI: 10.1259/bjr.20170843 -
Biology Open Mar 2022Heart rates of air-breathing diving animals can change on a short time scale due to the diving response during submergence. Heart rate is used frequently as a proxy for...
Heart rates of air-breathing diving animals can change on a short time scale due to the diving response during submergence. Heart rate is used frequently as a proxy for indirectly estimating metabolic rates on a fine time scale. However, most studies to date have been conducted on endothermic diving animals, and the relationships between metabolic rates and heart rates in ectothermic diving animals have not been well studied. Sea turtles are unique model organisms of diving ectotherms because they spend most of their life in the ocean and perform deep and/or long dives. In this study, we examined the relationship between heart rates and metabolic rates in captive loggerhead turtles, Caretta caretta, to estimate oxygen consumption rates during each dive based on heart rates. The oxygen consumption rates (V̇O2: mlO2 min-1 kg-1) and average heart rates (fH: beats min-1) were measured simultaneously in indoor tanks at water temperatures of 15-25°C. Our results showed that oxygen consumption rate was affected by heart rate and water temperature in loggerhead turtles. Based on the collected data, we formulated the model equation as V̇O2=0.0124fH+0.0047Tw - 0.0791. The equation can be used for estimating fine-scaled field metabolic rates in free-ranging loggerhead turtles. The results of this study will contribute to future comparative studies of the physiological states of ectothermic diving animals.
Topics: Animals; Diving; Heart Rate; Oxygen Consumption; Temperature; Turtles
PubMed: 35225332
DOI: 10.1242/bio.058952 -
International Journal of Molecular... Dec 2022Dissolved oxygen (DO) is deeply involved in preserving the life of cellular tissues and human beings due to its key role in cellular metabolism: its alterations may... (Review)
Review
Dissolved oxygen (DO) is deeply involved in preserving the life of cellular tissues and human beings due to its key role in cellular metabolism: its alterations may reflect important pathophysiological conditions. DO levels are measured to identify pathological conditions, explain pathophysiological mechanisms, and monitor the efficacy of therapeutic approaches. This is particularly relevant when the measurements are performed in vivo but also in contexts where a variety of biological and synthetic media are used, such as ex vivo organ perfusion. A reliable measurement of medium oxygenation ensures a high-quality process. It is crucial to provide a high-accuracy, real-time method for DO quantification, which could be robust towards different medium compositions and temperatures. In fact, biological fluids and synthetic clinical fluids represent a challenging environment where DO interacts with various compounds and can change continuously and dynamically, and further precaution is needed to obtain reliable results. This study aims to present and discuss the main oxygen detection and quantification methods, focusing on the technical needs for their translation to clinical practice. Firstly, we resumed all the main methodologies and advancements concerning dissolved oxygen determination. After identifying the main groups of all the available techniques for DO sensing based on their mechanisms and applicability, we focused on transferring the most promising approaches to a clinical in vivo/ex vivo setting.
Topics: Humans; Oxygen; Oxygen Consumption
PubMed: 36555613
DOI: 10.3390/ijms232415971 -
Journal of Assisted Reproduction and... Aug 2007In search for a new marker of preimplantation embryo viability the present study investigated oxygen consumption of individual cleavage stage murine embryos, and...
PURPOSE
In search for a new marker of preimplantation embryo viability the present study investigated oxygen consumption of individual cleavage stage murine embryos, and evaluated the predictive value regarding subsequent development to expanded blastocysts.
METHODS
In all, 248 embryos were investigated from 2 cell stage until blastocyst stage with individual measurement of oxygen consumption and recording of developmental stage. Cleavage stage embryos and morula were divided in groups according to their oxygen consumption, and odds ratios (OR) for subsequent development to expanded blastocyst were calculated.
RESULTS
Cleavage stage (2-8 cell) individual oxygen consumption was 0.16-0.20 nl O(2) h(-1), with a significant increase to 0.21-0.23 nl O(2) h(-1) at the morula stage followed by a more than twofold increase for the expanded blastocyst 0.47 nl O(2) h(-1). A significantly higher chance of reaching the expanded blastocyst stage was found in 4-cell embryos with high oxygen consumption, than embryos with low consumption (OR 2.25, 95% CI 1.04-4.90). Among 2-cell embryos the chance of low and high consumers was not significantly different. The method used in the present study somewhat compromised embryo development (51% blastocyst rate) compared to controls (80% blastocystrate) which could make our results less robust.
CONCLUSION
Preliminary data from the present study suggest that oxygen consumption in cleavage stage embryos may be an indicator, but a not a strong predictor, of subsequent development to expanded blastocysts.
Topics: Animals; Blastocyst; Cleavage Stage, Ovum; Embryonic Development; Female; Mice; Mice, Inbred C57BL; Oxygen; Oxygen Consumption; Pregnancy
PubMed: 17636441
DOI: 10.1007/s10815-007-9138-5 -
The Journal of Physiology May 19881. Oxygen consumption of contracting single muscle fibres of Rana temporaria and Xenopus laevis was investigated at 20 degrees C. 2. Single fibres of the tibialis...
1. Oxygen consumption of contracting single muscle fibres of Rana temporaria and Xenopus laevis was investigated at 20 degrees C. 2. Single fibres of the tibialis anterior muscle of Rana and the iliofibularis muscle of Xenopus were mounted in a chamber containing Ringer solution. The solution was stirred and its partial pressure of oxygen (PO2) was continuously measured polarographically. 3. Steady-state rates of oxygen consumption (VO2) of single fibres were determined as a function of twitch frequency (0.2-12 stimuli s-1, depending on the type of fibre). VO2 increased with twitch frequency until a plateau value (VO2,max) was reached. VO2,max of different fibres ranged from 0.042 to 0.169 nmol O2 s-1 mg-1 dry weight in Rana and from 0.045 to 0.412 nmol O2 s-1 mg-1 dry weight in Xenopus. Under VO2,max conditions oxygen availability was not the limiting factor. 4. VO2 after injection of the uncoupler carbonyl cyanide m-chlorophenylhydrazone (CCCP) into the chamber correlated with VO2,max, suggesting that VO2,max is determined by mitochondrial density. This suggestion was confirmed by the observation that a close relationship exists between VO2,max and succinate dehydrogenase activity in three different fibre types of Xenopus. 5. At VO2,max a considerable amount of oxygen was taken up after the twitch train by most fibres, indicating that the oxidative ATP synthesis cannot match ATP hydrolysis. Xenopus muscle fibres with high oxidative capacity did not show this phenomenon. 6. The results are discussed in relation to the occurrence of anoxic cores in muscle fibres and the maximum steady-state contractile activity attainable by the fibres.
Topics: Animals; Carbonyl Cyanide m-Chlorophenyl Hydrazone; Female; Muscle Contraction; Muscles; Oxidative Phosphorylation; Oxygen Consumption; Rana temporaria; Xenopus laevis
PubMed: 3261341
DOI: 10.1113/jphysiol.1988.sp017088 -
Scientific Reports May 2021Thoroughbreds have high maximal oxygen consumption and show hypoxemia and hypercapnia during intense exercise, suggesting that the peripheral environment in skeletal...
Thoroughbreds have high maximal oxygen consumption and show hypoxemia and hypercapnia during intense exercise, suggesting that the peripheral environment in skeletal muscle may be severe. Changes in metabolites following extreme alterations in the muscle environment in horses after exercise may provide useful evidence. We compared the muscle metabolites before and after supramaximal exercise to fatigue in horses. Six well-trained horses ran until exhaustion in incremental exercise tests. Biopsy samples were obtained from the gluteus medius muscle before and immediately after exercise for capillary electrophoresis-mass spectrometry analysis. In the incremental exercise test, the total running time and speed of the last step were 10.4 ± 1.3 (mean ± standard deviation) min and 12.7 ± 0.5 m/s, respectively. Of 73 metabolites, 18 and 11 were significantly increased and decreased after exercise, respectively. The heat map of the hierarchical cluster analysis of muscle metabolites showed that changes in metabolites were clearly distinguishable before and after exercise. Strenuous exercise increased many metabolites in the glycolytic pathway and the tricarboxylic acid cycle in skeletal muscle. Targeted metabolomic analysis of skeletal muscle may clarify the intramuscular environment caused by exercise and explain the response of working muscles to strenuous exercise that induces hypoxemia and hypercapnia in Thoroughbred horses.
Topics: Animals; Female; Horses; Male; Metabolomics; Muscle Fatigue; Muscle, Skeletal; Oxygen Consumption; Physical Conditioning, Animal
PubMed: 34045613
DOI: 10.1038/s41598-021-90834-y -
The British Journal of Radiology Jan 2019The complement system is an innate immune pathway typically thought of as part of the first line of defence against "non-self" species. In the context of cancer,... (Review)
Review
The complement system is an innate immune pathway typically thought of as part of the first line of defence against "non-self" species. In the context of cancer, complement has been described to have an active role in facilitating cancer-associated processes such as increased proliferation, angiogenesis and migration. Several cellular members of the tumour microenvironment express and/or produce complement proteins locally, including tumour cells. Dysregulation of the complement system has been reported in numerous tumours and increased expression of complement activation fragments in cancer patient specimens correlates with poor patient prognosis. Importantly, genetic or pharmacological targeting of complement has been shown to reduce tumour growth in several cancer preclinical models, suggesting that complement could be an attractive therapeutic target. Hypoxia (low oxygen) is frequently found in solid tumours and has a profound biological impact on cellular and non-cellular components of the tumour microenvironment. In this review, we focus on hypoxia since this is a prevailing feature of the tumour microenvironment that, like increased complement, is typically associated with poor prognosis. Furthermore, interesting links between hypoxia and complement have been recently proposed but never collectively reviewed. Here, we explore how hypoxia alters regulation of complement proteins in different cellular components of the tumour microenvironment, as well as the downstream biological consequences of this regulation.
Topics: Combined Modality Therapy; Complement System Proteins; Female; Gene Expression Regulation, Neoplastic; Humans; Male; Neoplasms; Oxygen Consumption; Prognosis; Signal Transduction; Treatment Outcome; Tumor Hypoxia; Tumor Microenvironment; Up-Regulation
PubMed: 29544344
DOI: 10.1259/bjr.20180069