Metabolic Rate Research Articles

Biochemical basis and therapeutic potential of mitochondrial uncoupling in cardiometabolic syndrome.

Mild uncoupling of oxidative phosphorylation is an intrinsic property of all mitochondria, allowing for adjustments in cellular energy metabolism to maintain metabolic homeostasis. Small molecule uncouplers have been extensively studied for their potential to increase metabolic rate, and recent research has focused on developing safe and effective mitochondrial uncoupling agents for the treatment of obesity and cardiometabolic syndrome (CMS). Here, we provide a brief overview of CMS and cover the recent mechanisms by which chemical uncouplers regulate CMS-associated risk-factors and comorbidities, including dyslipidemia, insulin resistance, steatotic liver disease, type 2 diabetes, and atherosclerosis. Additionally, we review the current landscape of uncoupling agents, focusing on repurposed FDA-approved drugs and compounds in advanced preclinical or early-stage clinical development. Lastly, we discuss recent molecular insights by which chemical uncouplers enhance cellular energy expenditure, highlighting their potential as a new addition to the current CMS drug landscape, and outline several limitations that need to be addressed before these agents can successfully be introduced into clinical practice.

Nasal breathing: a neglected factor in metabolic regulation?

Abstract Purpose Nasal breathing (NB) is a fundamental physiological process, and emerging research indicates its potential role in modulating resting metabolism, impacting energy expenditure and metabolic efficiency. This study investigates the impact of NB on resting metabolic rate (RMR), offering novel insights into metabolic regulation. Methods A prospective study was conducted on patients undergoing nasal surgery, with measurements taken before and 3 months after surgery. Metabolic rate assessments, anthropometric dimensions, and peak nasal inspiratory flow (PNIF) were recorded. Factors like age, sex, and health status were considered to control for confounding variables. Results A total of 83 patients were initially enrolled: 17 underwent septorhinoplasty (SRP), 61 septoplasty (ST) and 5 inferior turbinate reduction alone. 72 patients completed the follow-up. SRP patients exhibited significantly higher pre- and post-operative RMR compared to ST patients (p = 0.005), and this association was not observed when PNIF was included in the analysis (p > 0.05). Pre-operative and post-operative PNIF values significantly correlated with pre-operative and post-operative RMR (p = 0.049 and p = 0.005, respectively). Post-operative PNIF predicted post-operative RMR after confoundment adjustment in linear regression (β = – 0.043, p = 0.017). Importantly, total body weight increased after surgery (pre-op: 74 ± 14.6 kg versus post-op: 75.6 ± 15.5 kg, p < 0.001) due to an increment in muscle mass (pre-op: 52.3 ± 12 versus post-op: 55.5 ± 14, p < 0.01). Conclusion Preliminary analysis suggests a potential link between NB and RMR, emphasizing the overlooked role of nasal respiratory physiology in energy homeostasis. Surgery also elicited body composition alterations. Further research is needed to uncover the underlying mechanisms of this association. Understanding the impact of NB on RMR could underscore its significance in metabolic regulation, reinforcing the importance of nasal surgery on overall health. This study provides foundation for future investigations.

Assessment of hypoxia and its dynamic evolution in glioblastoma via qBOLD MRI: a comparative study with metformin treatment

BackgroundTo investigate the accuracy of quantitative blood oxygen level-dependent (qBOLD) magnetic resonance imaging (MRI) in identifying hypoxia within glioblastoma and explore dynamic changes in oxygenation status of glioblastoma with and without metformin administration.MethodsThree healthy and seven C6-bearing rats underwent 7-T qBOLD MRI. Oxygen extraction fraction (OEF) and cerebral metabolism rate of O2 (CMRO2) were calculated from qBOLD data. Tumor tissues were stained using hypoxia-inducible factor-1α (HIF-1α) and pimonidazole. The correlation between the hypoxia markers and corresponding qBOLD-based parameters was analyzed. Six C6-bearing rats were divided into metformin-treated and control groups for a longitudinal study of qBOLD imaging changes, with scans conducted on the 12th, 15th, and 18th day post-tumor implantation.ResultsIn healthy rats, gray matter showed higher values than white matter in T2, T2*, cerebral blood volume (CBV), and cerebral blood flow (CBF), whereas OEF was lower. Glioblastoma tissues exhibited elevated T2, T2*, CBV, and CBF but decreased OEF and CMRO2 relative to normal-appearing white matter. No significant correlation was found between staining scores from HIF-1α and pimonidazole. T2* and T2 values were negatively correlated with pimonidazole scores in tumor regions. As the tumor progressed, OEF values increased with intra-tissue variations, whereas CMRO2 decreased. Metformin delayed the reduction of T2 and T2* values, with significant differences in OEF and CMRO2 values compared to controls on day 18.ConclusionT2* and T2 values were significantly associated with the hypoxia status in glioma. Metformin could potentially mitigate the progression of hypoxia in glioblastoma, which can be tracked by qBOLD parameters.Relevance statementThis study demonstrates the potential of qBOLD parameters in assessing glioma dynamic oxygen metabolism and the efficacy of metformin as an anti-hypoxic agent, providing insights into improving glioblastoma treatment strategies.Key PointsThe study investigated qBOLD imaging’s accuracy in identifying hypoxia status within glioblastoma.qBOLD effectively assesses hypoxia and its dynamic evolution in glioblastoma.qBOLD parameters assist in identifying a suitable patient demographic for metformin treatment.Graphical

Taste triggers a homeostatic temperature control in hungry flies.

Hungry animals consistently show a desire to obtain food. Even a brief sensory detection of food can trigger bursts of physiological and behavioral changes. However, the underlying mechanisms by which the sensation of food triggers the acute behavioral response remain elusive. We have previously shown in Drosophila that hunger drives a preference for low temperature. Because Drosophila is a small ectotherm, a preference for low temperature implies a low body temperature and a low metabolic rate. Here, we show that taste-sensing triggers a switch from a low to a high temperature preference in hungry flies. We show that taste stimulation by artificial sweeteners or optogenetics triggers an acute warm preference, but is not sufficient to reach the fed state. Instead, nutrient intake is required to reach the fed state. The data suggest that starvation recovery is controlled by two components: taste-evoked and nutrient-induced warm preferences, and that taste and nutrient quality play distinct roles in starvation recovery. Animals are motivated to eat based on time of day or hunger. We found that clock genes and hunger signals profoundly control the taste-evoked warm preferences. Thus, our data suggest that the taste-evoked response is one of the critical layers of regulatory mechanisms representing internal energy homeostasis and metabolism.

Habitat degradation has species-specific effects on the stress response of coral reef fishes

Coral reefs are one of the world's most threatened ecosystems, with transition from coral- to algal-dominated habitats becoming increasingly common. While habitat degradation in other ecosystems can lead to heightened stress among individuals, thereby increasing energetic demands and reducing fitness, the effects of habitat degradation on stress and metabolic performance of coral reef fish is unknown. Therefore, we investigated whether cortisol levels (an indicator of stress), metabolic performance, behaviour, and growth, were influenced by habitat quality in three fish species with varying degrees of reliance on live coral. We reared newly-settled fishes (Pomacentrus amboinensis, P. moluccensis and Dascyllus aruanus) for three weeks in one of three habitat treatments: live coral, dead coral covered in turf algae and cyanobacteria, or a combination of the two. After three weeks we quantified each individuals metabolic performance, cortisol concentration, morphology, and habitat use. Pomacentrus moluccensis had higher cortisol concentrations in the dead coral treatment, compared to the live coral, whereas there was no difference in cortisol levels among habitat treatments for P. amboinensis or D. aruanus. Overall, metabolic performance (aerobic scope, standard and maximum metabolic rate) showed no consistent response to habitat treatments. Regarding morphology, we only found D. aruanus to be impacted, with individuals from the live coral treatment having a significantly higher mass than individuals from the dead coral treatment. Behavioural space-use analysis revealed that D. aruanus and P. moluccensis spent more time away from their habitats in the dead coral treatments, whereas the space-use of P. amboinensis was unaffected by habitat degradation. Understanding how coral loss affects stress levels and fitness of reef fishes is critical to predict future reef fish communities. This study highlights that vulnerability of reef fish to coral reef degradation is species-specific, and related to their reliance on live coral. These changes may provide a mechanistic explanation to observed population declines following coral loss and indicate that remaining individuals have reduced fitness potentially compromising the subsistence of future populations.

Taste triggers a homeostatic temperature control in hungry flies

Hungry animals consistently show a desire to obtain food. Even a brief sensory detection of food can trigger bursts of physiological and behavioral changes. However, the underlying mechanisms by which the sensation of food triggers the acute behavioral response remain elusive. We have previously shown in Drosophila that hunger drives a preference for low temperature. Because Drosophila is a small ectotherm, a preference for low temperature implies a low body temperature and a low metabolic rate. Here, we show that taste-sensing triggers a switch from a low to a high temperature preference in hungry flies. We show that taste stimulation by artificial sweeteners or optogenetics triggers an acute warm preference, but is not sufficient to reach the fed state. Instead, nutrient intake is required to reach the fed state. The data suggest that starvation recovery is controlled by two components: taste-evoked and nutrient-induced warm preferences, and that taste and nutrient quality play distinct roles in starvation recovery. Animals are motivated to eat based on time of day or hunger. We found that clock genes and hunger signals profoundly control the taste-evoked warm preferences. Thus, our data suggest that the taste-evoked response is one of the critical layers of regulatory mechanisms representing internal energy homeostasis and metabolism.

An improved dynamic metabolic model for application to biota

Any major nuclear facility must ensure the conservation of biodiversity regarding radiation protection of biota. A special concern is for tritium (3H) and radiocarbon (14C) transfer in wild mammals, birds and reptiles. Hydrogen and carbon are the main components of biological tissues and enter the life cycle. The present study improves the scientific bases of a previous model, analyses the uncertainty of input parameters and tests the model for a larger range of mammals and birds. The biological and metabolic half-times for organically bound tritium (OBT) and 14C are linked with energy metabolism and recent results are revised in relation with metabolic scaling. A large data base regarding basal metabolic rate (BMR), field metabolic rate (FMR), and organ mass is used for input information of the present model, which considers brain as a separate compartment. Metabolic energy partition in organs of active animal is defined and the factors affecting the metabolic rate are analysed. Body and ambient temperature, diet and habitat, and phylogeny are important factors considered in animal adaptation to environment. The available experimental data for carbon turnover rates in animals are analysed and it is observed that the experimental conditions are not appropriate for wild animals. The link between 13,14C and 134,137Cs turnover rate is analysed and the present metabolic approach is successfully tested for mammals and reptiles. Considering animal adaptation and the large data base for 134,137Cs, the radiological impact of accidental releases of 3H and 14C on biota can be pursued in the future research.

Antifatigue effect of okara protein hydrolysate supplementation during cycling exercise in men: a pre-post uncontrolled pilot study.

Prolonged exercise usually leads to exercise fatigue, which has a negative short-term impact on exercise performance and metabolic rate; thus, fatigue needs to be resolved. Okara is a protein-rich residue of soy processing. Enzyme hydrolysis is known to increase the content of branched-chain amino acids (BCAAs), which have been reported to confer benefits for exercise. The purpose of this study was to investigate the antifatigue effect of okara protein hydrolysate (OPH) on cycling exercise. A total of 16 male participants who habitually exercised (2 times or more per week and without participation in athletic contests) were instructed to receive 11.74 g of OPH once a day. They then completed two intense cycling exercise challenges before and after four weeks of supplementation. Exercise time and blood markers related to fatigue and energy metabolism were measured. The results showed that the time to exhaustion significantly increased after the treatment. The levels of lactate during exercise and at the end of exercise were significantly lower after treatment than before. Additionally, postexercise insulin sensitivity was increased after treatment. This study showed that OPH supplementation can promote endurance in exercise by decreasing the accumulation of fatigue-related metabolites during exercise and can promote energy recovery by increasing insulin function. These findings suggest that OPH has an antifatigue property.

Effects of elevated CO2 on the critical oxygen tension (Pcrit) and aerobic metabolism of two oxygen minimum zone (OMZ) hypoxia tolerant squat lobster species.

Marine invertebrates living in oxygen minimum zones (OMZ), where low pO2 and high pCO2 conditions co-occur, display physiological mechanisms allowing them to deal with these coupled stressors. We measured aerobic metabolic rate (MRa) and the critical oxygen tension (Pcrit), and calculated the oxygen supply capacity (α) of both the red (Grimothea monodon) and yellow (Grimothea johni) squat lobsters, under two pCO2 scenarios (~414 and 1400 μatm). We also measured haemolymph pH, haemocyanin oxygen binding affinity (p50), and haemolymph lactate content in both species under normoxia, low pCO2 hypoxia and high pCO2 hypoxia. Our results revealed that both species show extremely low Pcrit and P50 values. The MRa increased under high pCO2 condition in both species but hypoxia tolerance was not negatively impacted by pCO2. Furthermore, hypoxia tolerance is enhanced at high pCO2 in the yellow squat lobster, and although not statically significant, α value follows the same trend. The red squat lobster has a better pHe regulation and lower reliance on anaerobic metabolism. While the yellow squat lobster had a poorer pHe regulation during high pCO2 hypoxia, relying more on anaerobic metabolism. Our research suggests that elevated pCO2 is crucial on respiratory processes in hypoxia tolerant organisms, ameliorating the effects of hypoxia alone. Learning from OMZ adapted species contribute to better predicting climate change consequences on these important ecosystems.

OM-85 attenuates high-fat diet-induced obesity, insulin resistance, gut dysbiosis and nonalcoholic steatohepatitis in a murine model

BackgroundObesity is a global epidemic that is tied to a wide range of human disorders. Chronic consumption of a high-fat diet is linked to disruption of the intestinal microbiome, which drives obesity-related pathophysiology. Broncho-Vaxom® (OM-85), a bacterial lysate used for prophylaxis of recurrent respiratory tract infections, has both immunostimulatory and immunomodulatory functions. MethodsMale C57Bl/6 mice were maintained on normal control vs. high-fat diets for 8 weeks and treated or untreated with OM-85 or with the probiotic Lactobacillus plantarum, as a positive control. Mice were evaluated for weight gain, glucose tolerance, insulin tolerance, gut microbiome composition and non-alcoholic steatohepatitis (NASH). ResultsHigh-fat diet mice developed obesity, insulin resistance, NASH and gut dysbiosis with a shift from the Bacteroidetes phylum, such as Bacteroidales order and Muribaculaceae family organisms to Firmicutes groups, such as the Clostridium and Blautia genuses. Treatment with OM-85 led to 1) prevention of obesity, 2) prevention of insulin resistance, 3) attenuation of NASH and 4) attenuation of gut dysbiosis, with decreased levels of the organisms mentioned above and increases in Verrucomicrobiae phylum organisms such as Akkermansia family microbes as well as Muribaculaceae organisms. These shifts in the gut microbiome predict favorable effects on the short chain fatty acid profile in the gut and increased integrity of the intestinal barrier. Pathway analysis showed that OM-85 decreases rates of carbohydrate metabolism, providing an additional mechanism whereby OM-85 prevents obesity. ConclusionImmune modulators such as OM-85 should be investigated for their potential therapeutic effects on metabolism.

Comparative Physiological Impact of Television Viewing and Video Gaming in Young Adults: Cardiopulmonary and Metabolic Responses

IntroductionThis study examines cardiopulmonary and metabolic responses in young adults during two sedentary activities: watching television and playing seated video games. Sedentary behavior (SB), defined as activities with ≤1.5 METs performed while seated, is associated with increased cardiovascular risks and mortality. While television viewing correlates with adverse health outcomes, video gaming in adolescence is linked to fewer cardiovascular risks. However, their impacts on young adults remain unclear. MethodsTwelve male kinesiology students (mean age: 22.6 ± 2.1 years) from the Universidad de Santiago de Chile participated in a cross-sectional study. Two 80-minute sessions—television viewing and video gaming—were structured into Pre-Activity (10 min), Activity (60 min), and Post-Activity (10 min) phases. Oxygen consumption (VO₂), carbon dioxide production (VCO₂), heart rate (HR), and breathing parameters were measured. Energy expenditure (EE) and metabolic equivalents (METs) were calculated from expired gas samples. ResultsVideo gaming elicited significantly higher HR and breathing rates (p < 0.01), as well as greater VO₂, VCO₂, EE, and METs (p < 0.05) compared to television viewing, indicating higher metabolic and cardiovascular demand. However, the energy expenditure during gaming remained within the sedentary range, failing to exceed basal metabolic rates. ConclusionVideo gaming is more metabolically demanding than television viewing but does not qualify as light physical activity. These findings emphasize the need for public health strategies that differentiate between sedentary behaviors and promote more vigorous activities to mitigate sedentary lifestyle risks.

Agreement between fat-free mass from bioelectrical impedance analysis and dual-energy X-ray absorptiometry and their use in estimating resting metabolic rate in resistance-trained men.

This study aimed to determine the agreement between fat-free mass (FFM) estimates from bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA) and their use in estimating resting metabolic rate (RMR) in men undergoing resistance training. Thirty healthy resistance-trained men (22.7 ± 4.4 years, 70.0 ± 8.7 kg, 174.6 ± 6.7 cm, and 22.9 ± 2.3 kg/m2) were evaluated. The equation developed by Tinsley et al. (RMR = 25.9 × fat-free mass [FFM] + 284) was adopted to calculate the RMR. DXA was used as the reference method for FFM. Furthermore, FFM was also estimated by BIA using a spectral device. No significant difference (p > 0.05) was observed between DXA (1884.2 ± 145.5 kcal) and BIA (1849.4 ± 167.7 kcal) to estimate RMR. A positive and significant correlation (r = 0.89, p < 0.05) was observed between DXA and BIA estimates of RMR. The mean difference between methods indicated that BIA presented a bias of -34.8 kcal. These findings suggest that using FFM derived from DXA or BIA results in similar RMR estimates in resistance-trained men.

Cerebral hemodynamics and oxygen metabolism in patients with milder and severe forms of sickle cell disease and thalassemia.

Silent cerebral infarcts (SCIs) are present in patients with sickle cell disease (SCD) and thalassemia, but the pathophysiology of SCIs is not fully understood. Previous studies mainly focused on cerebral hemodynamics and oxygen metabolism in patients with severe SCD (HbSS/HbSβ°) but not in milder forms of SCD (HbSC/HbSβ+) and thalassemia despite the high prevalence of SCIs in these patients. In this work, we studied the cerebral hemodynamics and oxygen metabolism, and SCI lesion load in 75 severe and 26 mild adult SCD patients, 18 thalassemia patients (as anemic comparison group), and 30 healthy controls before and after a vasodilatory challenge with acetazolamide. Cerebral blood flow was significantly higher in patients with severe SCD and thalassemia compared to patients with mild SCD and controls (p < 0.05). Conversely, oxygen extraction fraction and cerebral metabolic rate of oxygen (CMRO2) were significantly lower in patients with severe SCD and thalassemia compared to other groups (p < 0.01). In contrast, no difference in SCI volumes was found between mild and severe SCD and thalassemia patients. After acetazolamide administration, oxygen delivery increased less in severe SCD and thalassemia patients compared to other groups (p < 0.01) and CMRO2 decreased only in severe SCD patients (p < 0.01). Given the reduced CMRO2 values in severe SCD and thalassemia patients, we conclude that reduced cerebral oxygen consumption in these patient groups is mostly related to anemia. Our data suggest that the pathophysiology of SCIs in patients with milder forms of SCD might be more related to prior episodes of anemia or other sickle cell-related factors.

Abundance and estimated food consumption of seabirds in the pelagic ecosystem in the eastern Indian sector of the Southern Ocean

Quantification of abundance and food consumption of seabirds are key to understand characteristics and ecological functions of local marine ecosystem due to their abundance and diversity in foraging areas, habitat, behavior, mobility and prey types. This study aimed to quantify seabird abundance in pelagic areas in the eastern Indian sector of the Southern Ocean (80–150E°) based on an at-sea observational study conducted during the 2018/19 austral summer season. We estimated food consumption by seabirds based on their biomass, estimated field metabolic rates, number of days spent in the areas, and diet composition. Among the five functional seabird groups (penguins, albatrosses/giant petrels, shearwaters, petrels/Charadriiformes, prions/storm-petrels), shearwaters, non-Antarctic resident, were the most dominant taxa both by abundance (15,650,000 birds) and biomass (9,332 tonnes) in the study area during the summer. Most of the prey consumed by all seabirds in the area was presumed to be Antarctic krill (55,504 tonnes) and pelagic fishes (91,695 tonnes), such as myctophids. Although the total food consumption by the seabirds during the summer (209,973 tonnes) was lower than that reported in the Antarctic neritic areas (e.g., 753,000 tonnes in the neighboring Prydz Bay region), the higher proportion of non-resident shearwaters in biomass and estimated food consumption (85%) were the characteristic of the study area. Our results highlight the characteristics of the ecological importance of the study area in which seabirds consume Antarctic krill and pelagic fishes in the upper layer of the water column, and its nutrients are easily transported by the seabirds as their subcutaneous fat or stomach oil to the outside of the areas.

Can High Temperatures Affect Body Size in Insects? The Case of Rubyspot Damselflies in the Colombian Western Andes

Basal metabolic rates (BMRs) increase with temperature and body mass. Environmental temperatures rapidly change in tropical mountains due to elevation (macro scale) and vegetation structure (micro scale). Thus, tropical mountains are good settings for testing the effects of temperature on BMRs. We measured the BMRs at four temperature ranges on six territorial and closely related species of Rubyspot damselflies (Hetaerina, Calopterygidae), which also share very similar behavior and morphology and are segregated by habitat and elevation across the Western Colombian Andes. We analyzed the effects of body mass, habitat, elevation, temperature, and sex on their BMRs, using a phylogenetic framework. We found that the main factors regulating their niche partition seemed to be environmental temperature, body size, and BMR. We found differences in their BMRs related to elevation when the temperatures were close to those experienced by the damselflies at their elevational range. As predicted, the larger species associated with colder habitats, forests, and highlands had higher BMRs. However, at high stressful temperatures, only the body mass was positively related to the BMR, showing that smaller individuals can keep their BMRs lower under high temperatures compared to bigger ones. Habitat use was not associated with changes in the BMR. Finally, phylogenetic reconstruction showed all species clustered in three clades. Each clade in the phylogenetic tree shares similar habitat preferences, pointing to a mixture of evolutionary history, thermal adaptations, and body mass differences as a possible explanation for the great diversity of these damselflies in a small area. Under the global warming scenario, we expect Rubyspots with smaller body sizes to be favored since they will tolerate higher temperatures, which would ultimately lead to populations with smaller body sizes overall, which could negatively affect their fitness.

Examination of Energy Needs and Low Energy Availability Among Historically Black College and University Female Student-Athletes

Low energy availability (LEA) is common among female student-athletes and contributes to reduced bone mineral density and hormonal dysfunction. However, limited research exists on student-athletes of color, making it difficult to generalize results across populations, particularly Historically Black Colleges and Universities (HBCUs) student-athletes. Objectives: This study examined the energy needs and LEA prevalence, with or without eating disorder (ED) risk, among HBCU female student-athletes. Methods: Twenty-seven female student-athletes (age = 19 ± 1 year; height = 166.9 ± 7.6 cm; weight = 68.8 ± 11.3 kg) completed baseline measures, including the Eating Disorder Inventory-3 (EDI-3), EDI-3 symptom checklist (EDI-SC), anthropometric measures, and resting metabolic rate (RMR). Participants maintained a dietary log to measure energy intake and wore a heart rate monitor to estimate exercise energy expenditures for 7 days. LEA was defined as &lt;30 kcal/kg of fat-free mass (FFM)/day. Results: The mean energy availability (15.9 ± 10.1 kcal/kg FFM/day) indicated 92.6% of participants (n = 25) displayed LEA; of those, 60% (n = 15) had LEA with ED risk. ED risk was identified in 59.3% of student-athletes (n = 13; EDI-3: n = 2; SC: n = 3; Both: n = 11). Interestingly, of the two student-athletes without LEA, one was identified at risk for EDs using both the EDI-3 and SC. Conclusions: HBCU female student-athletes face high risks of LEA and EDs, with most showing signs of both. This underscores the need for culturally sensitive interventions to improve EA and support mental health in this underserved group. Clinicians should focus on nutrition education and early ED identification to enhance long-term health and athletic performance.

Impact of recharge water source quality on Chlorella vulgaris growth and biomass: Strategies for eutrophication control in urban landscape lakes

Understanding the relationship between recharge water quality and algal metabolism is critical for managing eutrophication in urban landscape water bodies. This study investigates six landscape water bodies in Xi'an City, utilizing natural and reclaimed water recharge sources to cultivate and evaluate the growth and biomass composition of Chlorella vulgaris. The findings revealed that the growth and metabolic rate of C. vulgaris were faster in reclaimed water sources, whereas nitrogen (N) and phosphorus (P) conversion rates were higher in natural water sources. Redundancy and statistical analyses indicated that total nitrogen (TN) in reclaimed water was a major factor influencing C. vulgaris growth, contributing 74.3 % to its growth dynamics. In contrast, natural water sources did not significantly affect the growth characteristics of C. vulgaris. The biomass characteristics of C. vulgaris across different recharge water sources were similar, exhibiting a strong correlation with water quality. Environmental factors such as COD, N/P ratio, and PO4-P contributed most significantly to biomass accumulation. These findings provide a strategy for preventing and controlling eutrophication in landscape water bodies that utilize reclaimed water recharge sources in Xi'an City.

The dual timescales of gait adaptation: initial stability adjustments followed by subsequent energetic cost adjustments.

Gait adaptation during bipedal walking allows people to adjust their walking patterns to maintain balance, avoid obstacles and avoid injury. Adaptation involves complex processes that function to maintain stability and reduce energy expenditure. However, the processes that influence walking patterns during different points in the adaptation period remain to be investigated. We assessed split-belt adaptation in 17 young adults aged 19-35. We also assessed individual aerobic capacity to understand how aerobic capacity influences adaptation. We analyzed step lengths, step length asymmetry (SLA), mediolateral margins of stability, positive, negative and net mechanical work rates, as well as metabolic rate during adaptation. Dual-rate exponential mixed-effects regressions estimated the adaptation of each measure over two timescales; results indicate that mediolateral stability adapts over a single timescale in under 1 min, whereas mechanical work rates, metabolic rate, step lengths and SLA adapt over two distinct timescales (3.5-11.2 min). We then regressed mediolateral margins of stability, net mechanical work rate and metabolic rate on SLA during early and late adaptation phases to determine whether stability drives early adaptation and energetic cost drives late adaptation. Stability predicted SLA during the initial rapid onset of adaptation, and mechanical work rate predicted SLA during the latter part of adaptation. Findings suggest that stability optimization may contribute to early gait changes and that mechanical work contributes to later changes during adaptation. A final sub-analysis showed that aerobic capacity levels <36 and >43 ml kg-1min-1 resulted in greater SLA adaptation, underscoring the metabolic influences on gait adaptation. This study illuminates the complex interplay between biomechanical and metabolic factors in gait adaptation, shedding light on fundamental mechanisms underlying human locomotion.

Effects of musical tempo on human thermal comfort during interval exercise

Compared to steady-state exercise, thermal comfort during interval exercise varies. Moreover, research on the effects of musical tempo on subjective thermal perception, emotional state, and physiological responses in individuals performing interval exercise remains limited. Based on this, 22 participants were recruited for this study to simulate a gym environment within a climate chamber. The K5 metabolic analyzer combined with questionnaires was used to monitor the subjective responses and physiological parameters of participants during exercise, analyzing the effect of musical tempo on thermal comfort during interval exercise. Furthermore, by externalizing different tempos of music during the exercise phases of the experiment, participants' emotional states were induced to be either pleasant (positive) or boring (negative). The no-music working condition served as a control group for this experiment with no emotional induction. The research results indicate that music tempo affects the subjective thermal response, physiological response, and emotional state of the exercising population, with this influence showing clear differences and patterns. Notably, Regardless of the music tempo, the emotional index (MI) exhibited strong negative correlations with thermal sensation votes (TSV) (r = -0.76, -0.93), metabolic rate (MR) (r = -0.91, -0.95), and heart rate (HR) (r = -0.92, -0.94) across two exercise intensities. Based on these findings, a more adaptive PMV improvement model (PMV*) was developed using correlation analysis and regression fitting. This study provides important insights for the design of personalized exercise environments.

Enantioselective Metabolism of Mefentrifluconazole by Human Liver Microsomes.

A better understanding of the metabolic differences between chiral pesticide enantiomers in organisms is crucial for accurately assessing their risk. The enantioselective metabolism of mefentrifluconazole was investigated by the human liver microsome reaction system. The metabolic rate of S-mefentrifluconazole was found to be 4 times that of R-mefentrifluconazole. The chemical inhibitor method was used to further explore the cause of metabolic difference, and it was found that the inhibitors of CYP2C19 and CYP2C8 significantly reduced the metabolism of S-mefentrifluconazole (70.3-92.0%) and R-mefentrifluconazole (53.0-78.6%), respectively. CYP2C19 is a key metabolic enzyme of S-mefentrifluconazole. Molecular docking indicates that the internal energy of binding of R-mefentrifluconazole to CYP2C19 is too high, resulting in a positive docking fraction (0.1730 kJ/moL). Therefore, R-mefentrifluconazole cannot bind to CYP2C19 under natural conditions. CYP2C8 is the key metabolic enzyme of R-mefentrifluconazole. The lower docking energies (-37.80 kJ/moL for R-mefentrifluconazole and -35.64 kJ/moL for S-mefentrifluconazole) make CYP2C8 more capable of metabolizing R-mefentrifluconazole. This study provides essential data for exploring the toxicological assessment of mefentrifluconazole.