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Free Radical Biology & Medicine Sep 2023Reactive Oxygen Species (ROS) in the form of HO can act both as physiological signaling molecules as well as damaging agents, depending on their concentration and...
Reactive Oxygen Species (ROS) in the form of HO can act both as physiological signaling molecules as well as damaging agents, depending on their concentration and localization. The downstream biological effects of HO were often studied making use of exogenously added HO, generally as a bolus and at supraphysiological levels. But this does not mimic the continuous, low levels of intracellular HO production by for instance mitochondrial respiration. The enzyme d-Amino Acid Oxidase (DAAO) catalyzes HO formation using d-amino acids, which are absent from culture media, as a substrate. Ectopic expression of DAAO has recently been used in several studies to produce inducible and titratable intracellular HO. However, a method to directly quantify the amount of HO produced by DAAO has been lacking, making it difficult to assess whether observed phenotypes are the result of physiological or artificially high levels of HO. Here we describe a simple assay to directly quantify DAAO activity by measuring the oxygen consumed during HO production. The oxygen consumption rate (OCR) of DAAO can directly be compared to the basal mitochondrial respiration in the same assay, to estimate whether the ensuing level of HO production is within the range of physiological mitochondrial ROS production. In the tested monoclonal RPE1-hTERT cells, addition of 5 mM d-Ala to the culture media amounts to a DAAO-dependent OCR that surpasses ∼5% of the OCR that stems from basal mitochondrial respiration and hence produces supra-physiological levels of HO. We show that the assay can also be used to select clones that express differentially localized DAAO with the same absolute level of HO production to be able to discriminate the effects of HO production at different subcellular locations from differences in total oxidative burden. This method therefore greatly improves the interpretation and applicability of DAAO-based models, thereby moving the redox biology field forward.
Topics: Humans; Hydrogen Peroxide; Reactive Oxygen Species; Amino Acids; Oxygen Consumption; Oxygen
PubMed: 37392950
DOI: 10.1016/j.freeradbiomed.2023.06.030 -
Journal of the International Society of... Dec 2023Accumulation of body fat and dyslipidemia are associated with the development of obesity and cardiometabolic diseases. Moreover, the degree to which lipids can be... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
Accumulation of body fat and dyslipidemia are associated with the development of obesity and cardiometabolic diseases. Moreover, the degree to which lipids can be metabolized has been cited as a determinant of cardiometabolic health and prolonged endurance capacity. In the backdrop of increasing obesity and cardiometabolic diseases, lipid metabolism and its modulation by physical activity, dietary adjustments, and supplementation play a significant role in maintaining health and endurance. Food-derived oligopeptides, such as rice and soybean peptides, have been shown to directly regulate abnormal lipid metabolism or promote hypolipidemia and fat oxidation in cell culture models, animal models, and human studies. However, whether supplementation with oligopeptides derived from multiple food sources can promote lipid degradation and fat oxidation in athletes remains unclear. Therefore, in a randomized controlled crossover trial, we investigated the impact of food-derived oligopeptide supplementation before and during exercise on lipid metabolism in young male cyclists.
METHODS
Sixteen young male cyclists (age: 17.0 ± 1.0 years; height: 178.4 ± 6.9 cm; body mass: 68.7 ± 12.7 kg, body mass index: 21.5 ± 3.4 kg/m; maximum oxygen uptake: 56.3 ± 5.8 mL/min/kg) participated in this randomized controlled crossover trial. Each participant drank two beverages, one containing a blend of three food-derived oligopeptides (treatment, 0.5 g/kg body weight in total) and the other without (control), with a 2-week washout period between two experiments. The cyclists completed a one-day pattern protocol that consisted of intraday fasting, 30 min of sitting still, 85 min of prolonged exercise plus a 5-min sprint (PE), a short recovery period of 60 min, a 20-min time trial (TT), and recovery till next morning. Blood samples were collected for biochemical analyses of serum lipids and other biomarkers. We analyzed plasma triglyceride species (TGs), free amino acids (FAAs), and tricarboxylic acid (TCA) cycle intermediates using omics methods. In addition, exhaled gas was collected to assess the fat oxidation rate.
RESULTS
Five of 20 plasma FAAs were elevated pre-exercise (pre-Ex) only 20 min after oligopeptide ingestion, and most FAAs were markedly increased post PE and TT. Serum levels of TG and non-esterified fatty acids were lower in the experimental condition than in the control condition at the post PE and TT assessments, respectively. Further, the omics analysis of plasma TGs for the experimental condition demonstrated that most TGs were lower post PE and at the next fasting when compared with control levels. Simultaneously, the fat oxidation rate began to increase only 20 min after ingestion and during the preceding 85 min of PE. Levels of TCA cycle intermediates did not differ between the conditions.
CONCLUSIONS
The study noted that continuous ingestion of food-derived oligopeptides accelerated total body triglyceride breakdown, non-esterified fatty acid uptake, and fat oxidation during both sedentary and exercise states. Elevated circulating and intracellular FAA flux may modulate the selection of substrates for metabolic pathways in conjunction with the release of neuroendocrinological factors that slow down carbohydrate metabolism via acetyl coenzyme A feedback inhibition. This may increase the availability of fatty acids for energy production, with FAAs supplying more substrates for the TCA cycle. The findings of this study provide novel insight into strategies for promoting lipid metabolism in populations with dyslipidemia-related metabolic disorders such as obesity and for improving physiological functioning during endurance training. However, the absence of a non-exercising control group and verification of long-term supplementation effects was a limitation. Future studies will emphasize the impacts of whole protein supplementation as a control and of combined food-derived peptides or oligopeptides with probiotics and healthy food components on lipid metabolism in individuals who exercise.
Topics: Animals; Humans; Male; Adolescent; Lipid Metabolism; Cross-Over Studies; Oxygen Consumption; Oxygen; Oligopeptides; Amino Acids; Cardiovascular Diseases; Dietary Supplements; Lipids
PubMed: 37674290
DOI: 10.1080/15502783.2023.2254741 -
Journal of Sports Science & Medicine Dec 2023Being able to tread water effectively can improve the likelihood of survival following accidental immersion. People tread water in various ways, ranging from rudimentary...
Being able to tread water effectively can improve the likelihood of survival following accidental immersion. People tread water in various ways, ranging from rudimentary 'doggy-paddle' to more elaborate techniques like the eggbeater, but little is known about the energetic and cognitive requirements of treading water. We therefore aimed to measure the demands of treading water techniques for people of different experience levels. Three cohorts, comprising 21 adult water treading experts (water polo players), 15 intermediate swimmers and 16 inexperienced swimmers, treaded water for 3 min each using four different techniques while cognitive and energetic economy measures were taken. For inexperienced swimmers, the flutter kick and breaststroke patterns produced the lowest self-reported physical and task load (rating of perceived exertion, NASA task load index), while cognitive (probe reaction time), cardiac (heart rate) and metabolic (oxygen consumption) load did not differ between techniques. In contrast, for expert water treaders, both breaststroke and eggbeater patterns produced lower cognitive, cardiac and metabolic loads. For intermediate swimmers, breaststroke resulted in the lowest cardiac and metabolic loads, as well as self-reported task load. Probe reaction time was highest while performing the eggbeater technique, indicating that this technique was challenging to coordinate and cognitively demanding. While the energetic demands of antiphase kicking patterns (such as eggbeater in experts or flutter kick in beginners) may be similarly low, the symmetric coordination of upright breaststroke may explain why this pattern's cognitive economy was favourable for all groups. As the eggbeater can be challenging to perform for many people, an upright breaststroke technique is an adequate alternative to adopt in survival situations.
Topics: Adult; Humans; Swimming; Water Sports; Oxygen Consumption; Cognition
PubMed: 38045755
DOI: 10.52082/jssm.2023.726 -
European Journal of Applied Physiology Mar 2024To determine the effects of load carriage in normoxia and normobaric hypoxia on ventilatory responses, hemodynamics, tissue oxygenation, and metabolism.
PURPOSE
To determine the effects of load carriage in normoxia and normobaric hypoxia on ventilatory responses, hemodynamics, tissue oxygenation, and metabolism.
METHODS
Healthy males (n = 12) completed 3 randomly ordered baseline graded exercise tests in the following conditions: (1) unloaded normoxic (U: FO = 20.93%), (2) loaded (~ 30 kg) normoxic (LN), and (3) loaded hypoxic simulating ~ 3650 m (LH: FO = ~ 13%). Thereafter, experimental exercise trials were completed in quasi-randomized order (i.e., U completed first) consisting of 3 × 10 min of walking (separated by 5 min seated rest) with stages matched with the U condition (in ascending order) for relative intensity, absolute oxygen consumption ([VO]; 1.7 L min), and walking speed (1.45 ± 0.15 m s).
RESULTS
Load carriage increased perceived exertion and reduced VO (LN: - 7%; LH: - 32%; p < 0.05). At matched VO, stroke volume and tidal volume were reduced and maintained with LN and LH vs. U, respectively (p < 0.05). Increases in cardiac output and minute ventilation at matched VO (with LH) and speed (with LN and LH), were primarily accomplished via increases in heart rate and breathing frequency (p < 0.05). Cerebral oxygenated hemoglobin (OHHb) was increased at all intensities with LN, but deoxygenated hemoglobin and total hemoglobin were increased with LH (p < 0.05). Muscle oxygen kinetics and substrate utilization were similar between LN and U, but LH increased CHO dependence and reduced muscle OHHb at matched speed (p < 0.05).
CONCLUSION
Load carriage reduces cardiorespiratory efficiency and increases physiological strain, particularly in hypoxic environments. Potential load carriage-induced alterations in cerebral blood flow may increase the risk for altitude illnesses and requires further study.
Topics: Male; Humans; Hypoxia; Respiration; Exercise; Oxygen Consumption; Oxygen; Hemoglobins
PubMed: 37740748
DOI: 10.1007/s00421-023-05320-2 -
Biology Open Dec 2023Spring conditions, especially in temperate regions, may fluctuate abruptly and drastically. Environmental variability can expose organisms to temperatures outside of...
Spring conditions, especially in temperate regions, may fluctuate abruptly and drastically. Environmental variability can expose organisms to temperatures outside of their optimal thermal ranges. For ectotherms, sudden changes in temperature may cause short- and long-term physiological effects, including changes in respiration, morphology, and reproduction. Exposure to variable temperatures during active development, which is likely to occur for insects developing in spring, can cause detrimental effects. Using the alfalfa leafcutting bee, Megachile rotundata, we aimed to determine if oxygen consumption could be measured using a new system and to test the hypothesis that female and male M. rotundata have a thermal performance curve with a wide optimal range. Oxygen consumption of M. rotundata pupae was measured across a large range of temperatures (6-48°C) using an optical oxygen sensor in a closed respirometry system. Absolute and mass-specific metabolic rates were calculated and compared between bees that were extracted from their brood cells and those remaining in the brood cell to determine whether pupae could be accurately measured inside their brood cells. The metabolic response to temperature was non-linear, which is an assumption of a thermal performance curve; however, the predicted negative slope at higher temperatures was not observed. Despite sexual dimorphism in body mass, sex differences only occurred in mass-specific metabolic rates. Higher metabolic rates in males may be attributed to faster development times, which could explain why there were no differences in absolute metabolic rate measurements. Understanding the physiological and ecological effects of thermal environmental variability on M. rotundata will help to better predict their response to climate change.
Topics: Bees; Female; Male; Animals; Temperature; Medicago sativa; Metamorphosis, Biological; Pupa; Hot Temperature
PubMed: 38156711
DOI: 10.1242/bio.060213 -
Arquivos Brasileiros de Cardiologia Dec 2023Central Illustration : Prediction of Peak Oxygen Consumption in Patients with Heart Disease Based on Performance on the Timed Up and Go Test CPET: cardiopulmonary...
BACKGROUND
Central Illustration : Prediction of Peak Oxygen Consumption in Patients with Heart Disease Based on Performance on the Timed Up and Go Test CPET: cardiopulmonary exercise test; TUG: timed up and go test; VO2peak: peak oxygen consumption.
BACKGROUND
The use of the timed up and go (TUG) test to assess cardiorespiratory fitness in patients with heart disease has not been well defined in the literature.
OBJECTIVES
Test the association between TUG and peak oxygen consumption (VO2peak), construct an equation based on TUG to predict VO2peak, and determine a cutoff point to estimate VO2peak ≥ 20 mL/kg/min.
METHODS
This cross-sectional study included 201 patients with coronary artery disease or heart failure, between 36 and 92 years of age, who underwent TUG and cardiopulmonary exercise test. Correlation, ROC curve, multiple linear regression, and Bland-Altman analyses were performed. The significance level was set at p < 0.05.
RESULTS
The mean age of the total sample was 67 ± 13 years, and 70% of participants were male. The mean VO2peak was 17 ± 6 mL/kg/min, and the mean TUG time was 7 ± 2.5 seconds. The correlation between VO2peak and TUG was r = -0.54 (p < 0.001), and R2 was 0.30. The following equation was developed based on TUG: V O 2 peak = 33.553 + ( - 0.149 × age ) + ( - 0.738 × TUG ) + ( - 2.870 × sex ) ; a value of 0 was assigned to the male sex and 1 to the female sex (adjusted R: 0.41; adjusted R2: 0.40). The VO2peak estimated by the equation was 18.81 ± 3.2 mL/kg/min, and the VO2peak determined by cardiopulmonary exercise test was 18.18 ± 5.9 mL/kg/min (p > 0.05). The best cutoff point in the TUG for VO2peak ≥ 20 mL/kg/min was ≤ 5.47 seconds (area under the curve: 0.80; 95% confidence interval: 0.74 to 0.86).
CONCLUSIONS
TUG and VO2peak showed a significant association. A prediction equation for VO2peak was developed and validated internally with good performance. The cutoff point in the TUG to predict VO2peak ≥ 20 mL/kg/min was ≤ 5.47 seconds.
Topics: Humans; Male; Female; Middle Aged; Aged; Aged, 80 and over; Cross-Sectional Studies; Postural Balance; Time and Motion Studies; Exercise Test; Heart Failure; Oxygen Consumption
PubMed: 38126569
DOI: 10.36660/abc.20230338 -
Journal of Exercise Science and Fitness Oct 2023Enhancement in maximal oxygen consumption (VO) induced by hypoxic training is important for both athletes and non-athletes. However, the lack of comparison of multiple... (Review)
Review
BACKGROUND
Enhancement in maximal oxygen consumption (VO) induced by hypoxic training is important for both athletes and non-athletes. However, the lack of comparison of multiple paradigms and the exploration of related modulating factors leads to the inability to recommend the optimal regimen in different situations. This study aimed to investigate the efficacy of seven common hypoxic training paradigms on VO and associated moderators.
METHODS
Electronic (i.e., five databases) and manual searches were performed, and 42 studies involving 1246 healthy adults were included. Pairwise meta-analyses were conducted to compare different hypoxic training paradigms and hypoxic training and control conditions. The Bayesian network meta-analysis model was applied to calculate the standardised mean differences (SMDs) of pre-post VO alteration among hypoxic training paradigms in overall, athlete, and non-athlete populations, while meta-regression analyses were employed to explore the relationships between covariates and SMDs.
RESULTS
All seven hypoxic training paradigms were effective to varying degrees, with SMDs ranging from 1.45 to 7.10. Intermittent hypoxia interval training (IHIT) had the highest probability of being the most efficient hypoxic training paradigm in the overall population and athlete subgroup (42%, 44%), whereas intermittent hypoxic training (IHT) was the most promising hypoxic training paradigm among non-athletes (66%). Meta-regression analysis revealed that saturation hours (coefficient, 0.004; = 0.038; 95% CI [0.0002, 0.0085]) accounted for variations of VO improvement induced by IHT.
CONCLUSION
Efficient hypoxic training paradigms for VO gains differed between athletes and non-athletes, with IHIT ranking best for athletes and IHT for non-athletes. The practicability of saturation hours is confirmed with respect to dose-response issues in the future hypoxic training and associated scientific research.
REGISTRATION
This study was registered in the PROSPERO international prospective register of systematic reviews (CRD42022333548).
PubMed: 37854170
DOI: 10.1016/j.jesf.2023.09.001 -
Comparative Biochemistry and... Oct 2023In eukaryotes, the performances of an organism are dependent on body mass and chemically supported by the mitochondrial production of ATP. Although the relationship...
In eukaryotes, the performances of an organism are dependent on body mass and chemically supported by the mitochondrial production of ATP. Although the relationship between body mass and mitochondrial oxygen consumption is well described, the allometry of the transduction efficiency from oxygen to ATP production (ATP/O) is still poorly understood. Using a comparative approach, we investigated the oxygen consumption and ATP production of liver mitochondria from twelve species of mammals ranging from 5 g to 600 kg. We found that both oxygen consumption and ATP production are mass dependent but not the ATP/O at the maximal phosphorylating state. The results also showed that for sub-maximal phosphorylating states the ATP/O value positively correlated with body mass, irrespective of the metabolic intensity. This result contrasts with previous data obtained in mammalian muscles, suggesting a tissue-dependence of the body mass effect on mitochondrial efficiency.
Topics: Animals; Oxidative Phosphorylation; Mitochondria, Liver; Adenosine Triphosphate; Mitochondria; Mammals; Oxygen Consumption
PubMed: 37479023
DOI: 10.1016/j.cbpa.2023.111490 -
Metabolic Demands and Kinematics During Level Walking in Darkness With No Vision or With Visual Aid.Military Medicine Jul 2023Uniformed services commonly perform foot-borne operations at night, while using visual aid in terms of night vision goggles (NVG). During slow-level walking, complete...
INTRODUCTION
Uniformed services commonly perform foot-borne operations at night, while using visual aid in terms of night vision goggles (NVG). During slow-level walking, complete lack of visual input alters kinematics and markedly increases the metabolic demand, whereas the effect on kinematics and energy expenditure of restricting the peripheral visual field by wearing NVG is still unknown. The purpose was to evaluate whether metabolic demands and kinematics during level walking are affected by complete darkness with and without visual aid.
MATERIALS AND METHODS
Eleven healthy men walked on a treadmill (inclination: +2.3°, velocity: 4 km/h) with full vision in a lighted laboratory (Light), and in complete darkness wearing either a blindfold (Dark), or restricting the visual field to about 40° by wearing monocular (Mono) or binocular (Bino) NVG. Oxygen uptake ($\dot{\text{V}}$O2) was measured to evaluate metabolic demands. Inertial measurement units were used to estimate kinematics, and the outcome was validated by using a motion capture system. Ratings of perceived exertion, discomfort, and mental stress were evaluated after each condition using a Borg ratio scale. Physiologic and kinematic variables were evaluated using repeated measures analysis of variance (ANOVA), whereas ratings were evaluated using non-parametric Friedman ANOVA.
RESULTS
$\dot{\text{V}}$ O2 was 20% higher in the Dark (1.2 ± 0.2 L/min) than the Light (1.0 ± 0.2 L/min) condition. Nominally, $\dot{\text{V}}$O2 in the Mono (1.1 ± 0.2 L/min) and Bino (1.1 ± 0.2 L/min) conditions fell in between those in the Light and Dark conditions but was not statistically different from either the Light or the Dark condition. Step length was shorter in the Dark (-9%, 1.22 ± 0.16 m) and Mono (-6%, 1.27 ± 0.09 m) conditions than in the Light condition (1.35 ± 0.11 m), whereas the Bino (1.28 ± 0.08 m) condition was not statistically different from either the Light or the Dark condition. The three conditions with no or limited vision were perceived more physically demanding, more uncomfortable, and more mentally stressful than the Light condition, and the Dark condition was perceived more mentally stressful than both NVG conditions.
CONCLUSIONS
The study confirms that complete lack of visual cues markedly reduces the mechanical efficiency during level walking, even under obstacle-free and highly predictable conditions. That $\dot{\text{V}}$O2 and step length values for the NVG conditions fell in between those of the Light and Dark conditions suggest that both foveal and peripheral vision may play important roles in optimizing the mechanical efficiency during level walking.
Topics: Humans; Male; Biomechanical Phenomena; Walking; Adult; Darkness; Energy Metabolism; Oxygen Consumption; Exercise Test; Eyeglasses
PubMed: 36331591
DOI: 10.1093/milmed/usac327 -
PloS One 2023Exercise capacity should be determined in all patients undergoing lung resection for lung cancer surgery and cardiopulmonary exercise testing (CPET) remains the gold... (Meta-Analysis)
Meta-Analysis
The association between cardiopulmonary exercise testing and postoperative outcomes in patients with lung cancer undergoing lung resection surgery: A systematic review and meta-analysis.
BACKGROUND
Exercise capacity should be determined in all patients undergoing lung resection for lung cancer surgery and cardiopulmonary exercise testing (CPET) remains the gold standard. The purpose of this study was to investigate associations between preoperative CPET and postoperative outcomes in patients undergoing lung resection surgery for lung cancer through a review of the existing literature.
METHODS
A search was conducted on PubMed, Scopus, Cochrane Library and CINAHL from inception until December 2022. Studies investigating associations between preoperative CPET and postoperative outcomes were included. Risk of bias was assessed using the QUIPS tool. A random effect model meta-analysis was performed. I2 > 40% indicated a high level of heterogeneity.
RESULTS
Thirty-seven studies were included with 6450 patients. Twenty-eight studies had low risk of bias. [Formula: see text] peak is the oxygen consumption at peak exercise and serves as a marker of cardiopulmonary fitness. Higher estimates of [Formula: see text] peak, measured and as a percentagege of predicted, showed significant associations with a lower risk of mortality [MD: 3.66, 95% CI: 0.88; 6.43 and MD: 16.49, 95% CI: 6.92; 26.07] and fewer complications [MD: 2.06, 95% CI: 1.12; 3.00 and MD: 9.82, 95% CI: 5.88; 13.76]. Using a previously defined cutoff value of > 15mL/kg/min for [Formula: see text] peak, showed evidence of decreased odds of mortality [OR: 0.55, 95% CI: 0.28-0.81] and but not decreased odds of postoperative morbidity [OR: 0.82, 95% CI: 0.64-1.00]. There was no relationship between [Formula: see text] slope, which depicts ventilatory efficiency, with mortality [MD: -9.60, 95% CI: -27.74; 8.54] however, patients without postoperative complications had a lower preoperative [Formula: see text] [MD: -2.36, 95% CI: -3.01; -1.71]. Exercise load and anaerobic threshold did not correlate with morbidity or mortality. There was significant heterogeneity between studies.
CONCLUSIONS
Estimates of cardiopulmonary fitness as evidenced by higher [Formula: see text] peak, measured and as a percentage of predicted, were associated with decreased morbidity and mortality. A cutoff value of [Formula: see text] peak > 15mL/kg/min was consistent with improved survival but not with fewer complications. Ventilatory efficiency was associated with decreased postoperative morbidity but not with improved survival. The heterogeneity in literature could be remedied with large scale, prospective, blinded, standardised research to improve preoperative risk stratification in patients with lung cancer scheduled for lung resection surgery.
Topics: Humans; Exercise Test; Lung Neoplasms; Prospective Studies; Oxygen Consumption; Lung
PubMed: 38060569
DOI: 10.1371/journal.pone.0295430