Oxygen Consumption Data Research Articles

Analysis of Workload of Corn Seed Planting Equipment Operators Integrated with Fertilization Equipment

Introduction: The use of corn seed planting tools integrated with fertilizing tools requires a lot of energy because workers act as controllers, so that it often causes physical and mental workloads. Workloads that are too heavy and exceed work capacity can cause fatigue. This fatigue will eventually cause pain. Objective: The objective of this study is to investigate the physical workload of operators in operating corn seed planting tools integrated with fertilizing tools in supporting SDGs. Method: The methodology used in this study includes pulse observations carried out 5 times on each operator for 3 working days. The pulse before and after implantation was measured by measuring the pulse on the wrist artery with the 10-beat method. Results and Discussion: The results showed that the worker's pulse can describe the workload as a manifestation of muscle movement when doing work. The greater the muscle activity, the greater the fluctuation of the pulse movement that occurs. The operator's workload is in the light to medium category. Oxygen consumption of workers is influenced by the intensity of the work done. Based on oxygen consumption data, it is known that the workload of this corn seed planting tool is still relatively low because workers still feel comfortable and safe while doing planting work. Research Implications: The practical and theoretical implications of this study prove that the greater the muscle activity, the greater the fluctuation of the pulse rate movement that occurs. Workers' oxygen consumption is influenced by the intensity of the work being done. Originality/Value: This study contributes that the worker's pulse rate indicates workload as a manifestation of muscle movement while working. The workload of this corn seed planter is still relatively low because workers still feel comfortable and safe when using the corn seed planter.

The influence of longitudinal bending stiffness on running economy and biomechanics in male and female runners

The purpose of this study was to evaluate the influence of different longitudinal bending stiffnesses (LBS) on running economy and lower extremity joint biomechanics in male and female runners. Thirty participants (15 F;15M) performed a treadmill protocol of five-minute randomised aerobic runs with four different footwear conditions varying in LBS: 16.1 N/mm; 32.7 N/mm; 46.1 N/mm; 90.1 N/mm. Biomechanical data was collected at the metatarsophalangeal (MTP) and ankle joints. Running economy was quantified via oxygen consumption data. Oxygen consumption observed no significant differences between footwear conditions (p = 0.960) or significant interaction between footwear and sex (p = 0.126). Stance time observed a significant difference between footwear conditions (p < 0.001), and a significant interaction of footwear and sex (p = 0.008), increasing in females as stiffness increased. At the MTP joint, a shoe effect was present for peak bending angle (p < 0.001), peak extension (p = 0.040) and flexion (p < 0.001) angular velocity, and energy generated at the joint (p = 0.010). There was also an interaction effect of peak MTP extension angular velocity (p = 0.044), with females slightly decreasing as stiffness increased, with no reaction from males. At the ankle joint, a shoe effect was present for peak dorsiflexion (p < 0.001) and plantarflexion (p < 0.001) angular velocity, peak negative power (p < 0.001) and energy absorbed at the joint (p < 0.001). Comparing the interaction between shoe condition and male/female runners, male and female runners reacted similarly to the increased LBS with no effect on running economy and subtle changes in the stance time and MTP angular velocity for female runners. While further research is needed in this area investigating aspects related to sex-specific optimal stiffness element location and geometry, it does not appear that the stiffness magnitude has a sex dependence.

Sublethal Toxicity Effects of the Organochlorine Insecticide Endosulfan on Oxygen Consumption Level and Gill Histopathology of Tilapia (Oreochromis Niloticus) Fry

The uncontrolled use of organochlorine insecticides in the agricultural sector has an impact on water pollution and threatens the lives of organisms in it. Pollutants can reduce water quality and interfere with the performance of fish organ systems, triggering stress and even death. The purpose of the study was to determine the sublethal effects of the organochlorine insecticide endosulfan on the level of oxygen consumption and histopathology of tilapia seed gills. The research was conducted at the Faculty of Fisheries and Marine Science, Universitas Airlangga, from March to May 2021. This study used a completely randomized design (CRD) experimental method. The treatment used was exposure to organochlorine endosulfan doses of 10%, 30%, 50%, and 70% with LC50-96 hours, which was observed for 28 days. Oxygen consumption data were analyzed by Analysis of Variance, followed by DMRT (Duncan's Multiple Range Test). While gill histopathology data were analyzed descriptively by comparing normal and abnormal gill histopathology. The results showed that the sublethal toxicity of the organochlorine insecticide endosulfan had a significant effect (p&lt;0.05) on the level of oxygen consumption and had an impact on the histopathological condition of the tilapia seed gills. The types of gill damage found were oedema, hyperplasia, lamellar fusion, hemorrhage, and necrosis.

A modelling approach to disentangle the factors limiting muscle oxygenation in smokers

Cigarette smoking is associated with a lower exercise capacity and lower muscle fatigue resistance. This is at least partly attributable to carboxyhaemoglobin (HbCO) in the blood that via reduction in the oxygen-carrying capacity, and the left-shift of the Hb-dissociation curve would reduce tissue oxygenation. On the other hand, a reduced oxygen uptake due to mitochondrial dysfunction would result in improved oxygenation. We used previously collected capillarisation, myoglobin and estimated cellular maximal muscle oxygen consumption data derived from succinate dehydrogenase-stained sections from the vastus lateralis muscle from six smokers and five non-smokers. These data were fed into an expanded Krogh tissue oxygenation model to assess whether an impaired muscle fatigue resistance in smokers is primarily due to HbCO or impaired mitochondrial respiration. The model showed that in smokers with 6% and 20% HbCO (causing a left-shift of the Hb-dissociation curve) average muscle oxygenation was reduced by 1.9% and 7.2%, respectively. Muscle oxygenation was increased by 13.3% when maximal mitochondrial respiration was reduced by 29%. A combination of a 29% reduction in maximal mitochondrial respiration and 20% HbCO led to no significant difference in muscle oxygenation from that in non-smokers. This indicates that while HbCO may explain the reduced exercise capacity after just one smoking session, in chronic smokers impaired mitochondrial respiration appears more important in reducing oxygen extraction and exercise capacity with only a small contribution of the left-shift of the Hb-dissociation curve.

Body Composition, Physical Function and Exercise Capacity in Chronic Obstructive Pulmonary Disease

Current literature yields unequivocal results regarding the effect of body composition on physical function in patients with chronic obstructive pulmonary disease and disproportionately includes a majority of males. The purpose of this study was to determine whether specific body composition measures are significantly associated with physical function and exercise capacity in patients with chronic obstructive pulmonary disease with equal representation of males and females. Independent variables included sex, total body mass, total body lean and fat mass, appendicular total mass, and appendicular lean and fat mass. Dependent variables included peak oxygen consumption, 6-minute walk distance and self-reported physical function. Patients (n = 170) with dual-energy X-ray absorptiometry data, 6-minute walk distance, and self-reported physical function were used for these analyses. A sub-set of 145 of these patients with peak oxygen consumption data were also analysed. Hierarchical multiple regression analysis was used to determine if sex and body composition measures correlated with physical function and exercise capacity and if they explained additional variance after controlling for disease severity. After controlling for disease severity, appendicular lean mass, total body fat mass, and sex explained an additional 16.5% of the variance in peak oxygen consumption (p < 0.001). Appendicular lean mass explained an additional 8.9% of the variance in 6-minute walk distance (p < 0.001) and an additional 2.5% of the variance in self-reported physical function (p = 0.057). Body composition measures may further predict exercise capacity, 6-minute walk distance, and self-reported physical function in patients with chronic obstructive pulmonary disease.

7-LB: Sodium–Glucose Cotransporter-2 Inhibitors (SGLT2i) Decrease Kidney Oxygen Consumption in Adults with Type 2 Diabetes (T2D)—A Randomized Clinical Trial Using 11C-Acetate Positron Emission Tomography (PET) Imaging

Kidney hypoxia has been proposed as key pathophysiological mechanism in the development of chronic kidney disease, potentially stemming from a mismatch between oxygen delivery and oxygen consumption. SGLT2i are kidney protective drugs that initially lower glomerular filtration rate (GFR). Accordingly, we hypothesized that SGLT2i lower kidney oxygen consumption by reducing GFR and associated tubular workload. Twenty adults with T2D (sex 80% male, age 68±6 years, BMI 30±4 kg/m2, HbA1c 7.5±0.9%, eGFR 76 ± 11 mL/min/1.73m2) received a 4-week treatment with SGLT2i ertugliflozin (ERTU) and matched placebo (PLB) in a randomized, double-blind cross-over study. Participants were treated with metformin and received maximal tolerable dose of an angiotensin receptor blocker. Whole-kidney oxygen consumption (Kmono) was measured by PET using 11C-acetate. GFR was measured by gold-standard iohexol clearance. Tubular sodium transport (TNa) was calculated by kidney sodium load (([arterial Na]*mGFR) - urinary sodium excretion). Kidney efficiency calculated as TNa/ Kmono. GFR was lower during ERTU (94 ± 14 mL/min) vs. PLB (99 ± 15 mL/min) treatment (p=0.02). Kmono was 0.086 ± 0.006 min-1 during ERTU and 0.091 ± 0.009 min-1 during PLB (p&amp;lt;0.01). Kidney sodium load (12.9 ± 1.90 vs 13.7 ± 2.22 mmol/min) and TNa (12.7 ± 1.87 vs 13.6 ± 2.18 mmol/min) were lower during ERTU (p=0.02 for both), while urinary sodium excretion (p=0.1) and TNa/ Kmono remained unchanged (p=0.7). TNa strongly associated with Kmono (r=0.50; p&amp;lt;0.0001). In conclusion, SGLT2i lowers mGFR, TNa, and kidney oxygen consumption, potentially decreasing hypoxia risk. SGLT2i treatment did not lower overall kidney efficiency, despite the ATP efficiency of cortical sodium transport. Additional data on cortex and medulla-specific oxygen consumption and multiparametric kidney MRI data will be presented at ADA. Disclosure A. Hesp: None. L. I. P. Snel: None. P. Schober: None. L. A. Schwarte: None. R. Boellaard: None. P. Bjornstad: Advisory Panel; AstraZeneca. Consultant; Bayer Inc., Bristol-Myers Squibb Company. Advisory Panel; Novo Nordisk, Lilly, Horizon Therapeutics plc, Boehringer Ingelheim (Canada) Ltd., LG Chem. D. van Raalte: Consultant; Boehringer Ingelheim and Eli Lilly Alliance, AstraZeneca, Merck &amp; Co., Inc. Research Support; Boehringer Ingelheim and Eli Lilly Alliance, AstraZeneca, Merck &amp; Co., Inc. Funding MSD

Feasibility and pilot study of passive heat therapy on cardiovascular performance and laboratory values in older adults

BackgroundChronic heat therapy may have beneficial effects on cardiovascular function. These effects may be more pronounced in older adults. We performed a pilot feasibility study of repeated heat therapy sessions in a hot tub (40.5 °C) in older adults while wearing a noninvasive hemodynamic monitor. As part of the protocol, the volunteers underwent cardiovascular performance testing pre- and post-intervention.MethodsFifteen volunteers > 50 years old underwent 8–10 separate 45-min hot tub session over 14 days in this exploratory and mixed methods trial. The participants had maximal oxygen consumption (VO2 max) and other cardiovascular data measured via exercise treadmill testing prior to and after all hot tub sessions. The participants also wore noninvasive fingertip volume clamp monitors while immerged in hot water that calculated systemic vascular resistance, heart rate, blood pressure, and cardiac output in order to ascertain the feasibility and utility of this data. Other laboratory studies were obtained pre- and post-intervention. The protocol was determined feasible if the heat therapy and cardiovascular testing was completed by at least 90% (14/15 subjects). Feasibility of the noninvasive monitor was determined by the fidelity of the results. Secondary exploratory outcomes were analyzed for differences to identify if they are acceptable to include in an efficacy trial.ResultsAll participants completed the study protocol identifying the feasibility of the protocol. The noninvasive hemodynamic monitors successfully recorded cardiac output, systemic vascular resistance, heart rate, and blood pressure with fidelity based on the analysis of recordings. In the secondary analyses, we found no difference in the pre- to post-intervention measurement of VO2 max but did find increased exercise duration following hot tub therapy compared with prior to the therapy (571 s versus 551 s).ConclusionsThe current pilot study protocol is feasible for the purpose of analyzing the effects of heat therapy and cardiovascular performance in older adults while wearing a noninvasive hemodynamic monitor and undergoing treadmill stress testing. Secondary analyses found increased exercise tolerance but no differences in VO2 max following heat sessions.

Latitudinal variation and plasticity in response to temperature in Geukensia demissa.

As global temperatures warm, species must adapt to a changing climate or transition to a different location suitable for their survival. Understanding the extent to which species are able to do so, particularly keystone species, is imperative to ensuring the survival of key ecosystems. The ribbed mussel Geukensia demissa is an integral part of salt marshes along the Atlantic coast of North America. Spatial patterns of genomic and phenotypic divergence have been previously documented, although their link with coastal environmental variation is unknown. Here, we study how populations of G. demissa in the northern (Massachusetts) and southern (Georgia) portions of the species range respond to changes in temperature. We combine assays of variation in oxygen consumption and RNA transcriptomic data with genomic divergence analyses to identify how separate populations of G. demissa may vary in distinct thermal environments. Our results show differences in constitutive oxygen consumption between mussels from Georgia and Massachusetts, as well as shared and disparate patterns of gene expression across temperature profiles. We also find that metabolic genes seem to be a strong component of divergence between these two populations. Our analysis highlights the importance of studying integrative patterns of genomic and phenotypic variation in species that are key for particular ecosystems, and how they might respond to further changes in climate.

A Novel Method for Measuring Lung Metabolism of Precision‐cut Lung Slices

Pulmonary diseases are associated with changes in metabolism. Cellular metabolism is dynamically regulated by signaling cascades at molecular levels and associated with the pathology at organ level. Improved understanding of cellular metabolism is necessary to investigate its role in disease and identify the potential targets for therapy. We have developed a real‐time method to adapt to Agilent XFe96 metabolic analyzer for precision‐cut lung slices (PCLS) so that compound effects on metabolism can be screened across multiple technical replicates. PCLS were cut in 3 mm maximum diameter to allow for fitting and adhering to XFe96 plate wells, which were pre‐coated with matrix gel. Once the PCLS were attached to the well bottom, the XFe96 cartridge probe can hold the tissue to measure, since the measurement volume is about 2‐6 µl, 200 micrometers (µm) above the lung tissue. This method generated reproducible oxygen consumption and extracellular acidification data in precision‐cut lung slices. We have optimized the conditions of oligomycin (OM) and Trifluoromethoxy carbonylcyanide phenylhydrazone (FCCP), rotenone and antimycin A to produce precision measurements. We have been able to utilize this technique to establish baseline metabolic rates for extracellular acidification and oxygen consumption and the dependency of those rates on mitochondrial function. In comparison with current cellular metabolic measurements, this method measures the whole tissue instead of an individual cell population. We have utilized this method to measure the effects of LPS treatment on PCLS metabolic function. Specifically, we have been able to demonstrate that LPS treatment not only leads to increased nitric oxide production in PCLS, but also reduces both glycolysis and spare respiratory capacity (SRC). This new method allows for the investigation of lung metabolism ex vivo and the screening of therapeutic targets for their interaction with lung metabolism.

The influence of midsole shear on running economy and smoothness with a 3D-printed midsole

ABSTRACT The objectives of this study were to first determine whether a newly designed 3D-printed midsole, configured with a mechanism to increase anterior-posterior deformation, could increase anterior midsole shear during the stance phase of running. We then wanted to determine whether these shoes could affect running economy and smoothness. Two footwear conditions, differing in midsole technology, were used in this study. The control condition consisted of a thermoplastic polyurethane midsole (TPU-Control), whereas the prototype shoes (3D-Shear) were constructed with a 3D-printed lattice midsole designed for greater anterior foot displacement during early to mid-stance. Twenty male participants ran on a treadmill for 6 min in each condition, and data were collected during the final 2 min. Midsole shear was measured using 3D kinematic data; running smoothness was quantified with peak acceleration and jerk magnitudes from the foot, sacrum, and head; and running economy was determined with oxygen consumption data. As hypothesised, the anterior midsole shear was greater in the 3D-Shear condition compared to the TPU-Control. The 3D-Shear did not improve running economy. Runners exhibited significantly lower peak accelerations at the sacrum, along with lower magnitudes of jerk at the foot, sacrum, and head in the 3D-Shear condition, indicating smoother running patterns.

Modeling the metabolic reductions of a passive back-support exoskeleton.

Despite several attempts to quantify the metabolic savings resulting from the use of passive back-support exoskeletons (BSEs), no study has modeled the metabolic change while wearing an exoskeleton during lifting. The objectives of this study were to: 1) quantify the metabolic reductions due to the VT-Lowe's exoskeleton during lifting; and 2) provide a comprehensive model to estimate the metabolic reductions from using a passive BSE. In this study, 15 healthy adults (13 males, 2 females) of ages 20-34 yr (mean = 25.33, SD = 4.43) performed repeated freestyle lifting and lowering of an empty box and a box with 20% of their bodyweight. Oxygen consumption and metabolic expenditure data were collected. A model for metabolic expenditure was developed and fitted with the experimental data of two prior studies and the without-exoskeleton experimental results. The metabolic cost model was then modified to reflect the effect of the exoskeleton. The experimental results revealed that VT-Lowe's exoskeleton significantly lowered the oxygen consumption by ∼9% for an empty box and 8% for a 20% bodyweight box, which corresponds to a net metabolic cost reduction of ∼12% and ∼9%, respectively. The mean metabolic difference (i.e., without-exo minus with-exo) and the 95% confidence interval were 0.36 and (0.2-0.52) W/kg for 0% body weight and 0.43 and (0.18-0.69) W/kg for 20% body weight. Our modeling predictions for with-exoskeleton conditions were precise, with absolute freestyle prediction errors of <2.1%. The model developed in this study can be modified based on different study designs, and can assist researchers in enhancing designs of future lifting exoskeletons.NEW & NOTEWORTHY We present a new model of the metabolic cost of repetitive lifting, and how that is affected by wearing a passive back support exoskeleton. We compute the effective biomechanical efficiencies of moving the body and a carried load during lifting, and determine the effect of an exoskeleton's efficiency on its metabolic reduction. This model is useful for understanding the effects of exoskeletons on the body and for designing future exoskeletons.

Normative Data of Maximal Oxygen Consumption (VO2 Max) among Healthy Young Adults: A Cross-sectional Study

Introduction: Maximal oxygen uptake (VO2 max) is the maximum quantity of oxygen a person can consume, and it remains constant over time despite increased exertion. The amount of oxygen consumed by the working muscles is measured by maximal oxygen consumption. The maximal oxygen uptake can be measured using maximal or submaximal tests, by gas analyser or field methods. The estimated VO2 max can be used to study people’s fitness and raise awareness about physical activity and lifestyle changes. Aim: To determine the VO2 max values using a direct method and provide normative data of VO2 max for healthy young adults in the age group of 18-25 years in both sexes. Materials and Methods: This cross-sectional study was approved by the Institutional Ethical Committee of RUHS College of Medical Sciences, Jaipur, Rajasthan, India. A total of 419 healthy young adults (male and female students) were recruited from RUHSCollege of Medical Sciences and MNIT College, Jaipur, Rajasthan, India from January 2019 to March 2020. Anthropometric data included age, height, weight according to the National Health and Nutrition Examination Survey (NHANES) and followed by measurement of VO2 max using a gas analyser of AD-Instrument (model-ML206). Collected data was entered in Microsoft excel. Paired t-test was used to compare mean and Standard Deviation (SD) of variables between male and female participants. The p-value of &lt;0.05 was considered as significant. Results: The study was conducted on 419 apparently healthy college students (275 male and 144 female). The mean VO2 max value for males was 45.30±7.35 mL/kg/min and for females it was 35.71±5.29 mL/kg/min, which was found to be significantly higher in males than in females. The mean VO2 max among the largest proportion of the males (27.63%) falls in the ‘Good’ category of cardiorespiratory fitness scale and the largest proportion of the females (32.63%) falls in the ‘Fair’ category of cardiorespiratory fitness scale. Conclusion: The value of VO2 max was lower in the Indian population than in the western population, when value obtained from this study was compared with the standard normative value of cardiorespiratory fitness. Therefore, the values obtained in this study could serve as a normative for the Indian population.

Machine learning analysis of electric arc furnace process for the evaluation of energy efficiency parameters

The electric arc furnace has been the subject of extensive research due to its complex and chaotic nature. Machine learning methods provide a powerful forensic examination of industrial processes as they exclude numerous assumptions and involve irregularities present in industrial conditions. In this study, different machine learning and data processing methods were used to evaluate the energy efficiency parameters of the electric arc furnace process. The dataset was collected over five years, in a steelmaking factory, with 42 features. This data was split into training and test sets, which were used for training and evaluation, respectively. With extensive data management, the data quality and machine learning model performance were improved. It was found that selected models display similar performance, yet the artificial neural network shows greater flexibility when changing targets. The results indicate that a data-centric rather than model-centric approach is better for improving model performance. Using the partial dependence plot and SHAP method, insight was gained into each parameter’s correlation with the target. It was found that the amount of hot heel (melted steel left in the furnace, to be re-heated) was the main factor disturbing the data quality and model performance. It was also demonstrated that data for total oxygen consumption should be divided from the oxygen used into refining and natural gas. This highly improves model performance. Employing a data-centric machine learning model to control and optimize main process parameters (with a small capital investment) leads to lower energy consumption for industrial processes.

The Effect of a Single Dose of Thiamine on Oxygen Consumption in Patients Requiring Mechanical Ventilation for Acute Illness: A Phase II, Randomized, Double-Blind, Placebo-Controlled Trial.

IMPORTANCE:Lower oxygen consumption is associated with worse survival in septic shock and in other forms of critical illness. No treatment that increases oxygen extraction, a key determinant of oxygen consumption, has been found. Thiamine is required for aerobic metabolism, and deficiency is common in the critically ill.OBJECTIVES:We evaluated the effect of thiamine on oxygen consumption in patients requiring mechanical ventilation for an acute illness.DESIGN:Phase II, randomized, double-blind, and placebo-controlled trial.SETTING AND PARTICIPANTS:ICUs in a tertiary care hospital in the United States. Patients admitted to the ICU and requiring mechanical ventilation were screened for enrollment.INTERVENTIONS:After enrollment, baseline measurement of oxygen consumption and baseline laboratories including lactate, central venous oxygen saturation, and pyruvate dehydrogenase, a single dose of 200 mg IV thiamine or placebo was administered. Oxygen consumption was then monitored for 6 additional hours and repeat laboratories were drawn at the end of the protocol.MAIN OUTCOMES AND MEASURES:The primary outcome was the change in oxygen consumption. Analysis was done using linear regression with a first-order autoregressive variance-covariance structure to account for repeated measures within subjects. Secondary outcomes included change in lactate, central venous oxygen saturation, and pyruvate dehydrogenase quantity and activity.RESULTS:Sixty-seven patients were enrolled. After excluding 11 patients due to inadequate quantity or quality of oxygen consumption data, 56 patients were included. There was no difference in change in oxygen consumption in the 6 hours after study drug. Results for secondary outcomes were similarly negative. In the prespecified subgroup of 18 thiamine deficient patients, there was a difference in the two oxygen consumption curves (p = 0.006), although no difference in median oxygen consumption or area under the curve.CONCLUSIONS AND RELEVANCE:A single dose of IV thiamine did not alter oxygen consumption in patients requiring mechanical ventilation for acute illness.

Abstract 12316: Carnitine O-octanoyltransferase Inhibition Attenuates Human Aortic Valve Interstitial Cell Calcification by Correcting Energetic Mitochondrial State

Background: Cardiovascular calcification is a critical pathology associated with increased cardiovascular risk, but there are no FDA-approved anti-calcification therapies. Through an unbiased screening approach, we previously identified carnitine O-octanoyltransferase (CROT) as a novel contributing factor to vascular calcification, but whether it can inhibit calcification in cardiac valves remains unknown. Here we investigated CROT-associated mechanisms of calcification in human valvular interstitial cells (VICs). Methods and Results: Human VICs were isolated from aortic valve leaflets of patients undergoing valve replacement surgeries at Brigham and Women’s Hospital, and cultured in osteogenic medium (OM) to induce calcification. OM increased CROT mRNA expression (1.83±0.41 fold-change; p&lt;0.05). Tissue-nonspecific alkaline phosphatase activity, a key regulator of calcification, was also increased by OM (8.80±3.81 fold-change; p&lt;0.001) and reduced by CROT siRNA treatment (0.48±0.19 fold-change; p&lt;0.01). CROT siRNA decreased calcium deposition (Alizarin red staining; &gt;99.9%; p&lt;0.001). We previously showed that mitochondria dysfunction contributes to vascular calcification. We therefore, assessed mitochondrial function in VICs by measuring oxygen consumption rate and extracellular acidification rate. Basal and maximal respiration, spare respiratory capacity and ATP production increased in VICs after OM stimulation (1.73±0.48, p&lt;0.01; 1.75±0.34, p&lt;0.01; 2.11±0.63, p&lt;0.05; 1.75±0.38, p&lt;0.05; respectively), indicating mitochondrial dysfunction. These parameters were corrected to normal state followed by CROT siRNA treatment. The combined data of oxygen consumption and extracellular acidification rates indicated that osteogenic condition induced mitochondria energetic state that was corrected to quiescent state by CROT siRNA treatment. Conclusions: CROT promotes calcification of human aortic VICs. CROT inhibition attenuates the calcification of VICs via correcting mitochondrial dysfunction induced by osteogenic environment. CROT inhibition is an attractive approach as a therapy for aortic valve calcification, a major unmet medical need.

Scaling the peak and steady-state aerobic power of running and walking humans.

The first aim of this experiment was to evaluate the appropriateness of linear and non-linear (allometric) models to scale peak aerobic power (oxygen consumption) against body mass. The possibilities that oxygen consumption would scale allometrically across the complete metabolic range, and that the scaling exponents would differ significantly between basal and maximal-exercise states, were then evaluated. It was further hypothesised that the scaling exponent would increase in a stepwise manner with elevations in exercise intensity. Finally, the utility of applying the scaling exponent derived for peak aerobic power to another population sample was evaluated. Basal, steady-state walking and peak (treadmill) oxygen-consumption data were measured using 60 relatively homogeneous men (18-40year; 56.0-117.1kg), recruited across five mass classes. Linear and allometric regressions were applied, with the utility of each scaling method evaluated. Oxygen consumption scaled allometrically with body mass across the complete metabolic range, and was always superior to both ratiometric analysis and linear regression. The scaling exponent increased significantly from rest (mass0.57) to maximal exercise (mass0.75; P < 0.05), but not between steady-state walking (mass0.87) and maximal exercise (P > 0.05). When used with an historical database, the maximal-exercise exponent successfully removed the mass bias. It has been demonstrated that the oxygen consumption of healthy humans scales allometrically with body mass across the entire metabolic range. Moreover, only two scaling exponents (rest and exercise) were required to produce mass-independent outcomes from those data. Accordingly, ratiometric and linear regression analyses are not recommended as scaling methods.

Oxygen Uptake Plateau Diagnosis Using a New Developed Segmented Regression Estimation Method for Autocorrelated Data.

Some proposals for oxygen uptake plateau identification are based on linear regression adaptations. However, linear regression does not adequately explain the oxygen uptake nonlinear dynamics. Recently, segmented regression was considered as an alternative to fit this dynamics, by performing an approximation by straight line segments, which provided a satisfactory fit. In this context, the non-plateau and plateau hypotheses were verified by means of a Wald-type test. This work aims to extend these proposals to scenarios with autocorrelated data. We propose an algorithm to estimate the segmented regression model under autocorrelation using generalized least squares and suggest a bootstrap method to resample from the null distribution of Wald's statistic. The performance of the estimate and methods of the plateau diagnosis were evaluated via Monte Carlo experiments. The empirical results show that, under autocorrelation, the proposed estimator performs better when compared to the classic method, mainly in scenarios with small sample sizes and moderate/strong autocorrelation structure. The simulations also showed that the plateau diagnosis test has a coherent empirical Type 1 Error probability and good power. We proposed an alternative to estimate the parameters of a segmented regression model for autocorrelated data and an oxygen consumption plateau bootstrap test, and concluded the methods present good performance under simulated and applied case studies. The proposed method was used to model real oxygen consumption data. Empirical evidence shows that the methods can be used to objectively identify the plateau in oxygen consumption only by specifying a tolerable significance level.

How does external lateral stabilization constrain normal gait, apart from improving medio-lateral gait stability?

Background: The effect of external lateral stabilization on medio-lateral gait stability has been investigated previously. However, existing lateral stabilization devices not only constrain lateral motions but also transverse and frontal pelvis rotations. This study aimed to investigate the effect of external lateral stabilization with and without constrained transverse pelvis rotation on mechanical and metabolic gait features. Methods: We undertook two experiments with 11 and 10 young adult subjects, respectively. Kinematic, kinetic and breath-by-breath oxygen consumption data were recorded during three walking conditions (normal walking (Normal), lateral stabilization with (Free) and without transverse pelvis rotation (Restricted)) and at three speeds (0.83, 1.25 and 1.66 m s−1) for each condition. In the second experiment, we reduced the weight of the frame, and allowed for longer habituation time to the stabilized conditions. Results: External lateral stabilization significantly reduced the amplitudes of the transverse and frontal pelvis rotations, in addition to medio-lateral, anterior–posterior, and vertical pelvis displacements, transverse thorax rotation, arm swing, step length and step width. The amplitudes of free vertical moment, anterior–posterior drift over a trial, and energy cost were not significantly influenced by external lateral stabilization. The removal of pelvic rotation restrictions by our experimental set-ups resulted in normal frontal pelvis rotation in Experiment 1 and significantly higher transverse pelvis rotation in Experiment 2, although transverse pelvis rotation still remained significantly less than in the Normal condition. Step length increased with the increased transverse pelvis rotation. Conclusion: Existing lateral stabilization set-ups not only constrain medio-lateral motions (i.e. medio-lateral pelvis displacement) but also constrain other movements such as transverse and frontal pelvis rotations, which leads to several other gait changes such as reduced transverse thorax rotation, and arm swing. Our new set-ups allowed for normal frontal pelvis rotation and more transverse pelvis rotation (yet less than normal). However, this did not result in more normal thorax rotation and arm swing. Hence, to provide medio-lateral support without constraining other gait variables, more elaborate set-ups are needed.

Reliability and Validity of the Lactate Pro 2 Analyzer

ABSTRACT This study evaluated the reliability of the portable Lactate Pro 2 analyzer (LP2), and its validity compared to a laboratory-based analyzer, YSI 1500 Sport (YSI). Blood samples (n = 258) were collected during 44 graded incremental rowing tests, with data from 17 tests used to quantify load, heart rate, and oxygen consumption at lactate threshold. Inter-LP2 reliability was high with coefficient of variation = 3.3%; Bland Altman 95% limits of agreement varied from ± 0.3 mmol.L−1 for blood lactate (BLa) ≤4.0 mmol.L−1 to −1.6 to +1.4 mmol.L−1 for BLa >8.0 mmol.L−1, with minimal systematic bias. Despite LP2 measurements being ~1.42 times higher than YSI measurements, no significant differences (P > .05) were detected when quantifying load, heart rate, or oxygen consumption data at lactate threshold. The results support using different LP2 devices interchangeably, especially when BLa ≤ 8 mmol.L−1, and using the LP2 to identify training intensities at lactate threshold.

Thermoset materials characterization by thermal desorption or pyrolysis based gas chromatography-mass spectrometry methods

Thermoset materials characterization is often limited to solid state analytical techniques such as IR, NMR, DSC, TGA and mechanical testing. Alternatively, their off-gassing behavior can also be evaluated using GC based techniques such as TD-GC-MS, allowing this method to be applied to thermoset materials analyses such as identification, aging characterization, and formulation optimization. As an overview, common thermoset materials were evaluated by analyzing their gaseous degradation products via TGA-based pyrolysis and subsequent TD-GC-MS for the identification of representative volatile signatures. It is thereby possible to distinguish different classes of phenolic materials or cured epoxy resins, as well as their amine or anhydride curatives. Additionally, this method enabled quantification of a volatile fragment (bisphenol A, BPA) which is associated with oxidation of epoxy/amine thermoset materials. The amount of evolved BPA increased linearly with aging time and this trend exhibits linear Arrhenius behavior over the temperature range (80–125 °C) studied, in agreement with oxidation sensitivies based on oxygen consumption data. Further, TD-GC-MS was used to explore how off-gassing of residual anhydride curative from an epoxy/anhydride material depends on formulation stoichiometry. Even in formulations that theoretically contained enough epoxy to consume all anhydride (1:1 stoichiometry), an imperfect final cure state resulted in residual anhydride which could evolve from the material. For such materials, a slightly epoxy-rich formulation is required to ensure that the material contains no residual unreacted anhydride. Analysis of volatiles generated by thermal exposure is an attractive characterization approach enabling compositional analysis as well as complementary diagnostics for materials degradation.