Oxygen Consumption Characteristics Research Articles

Seasonal Variations in Characteristics of Oxygen Consumption by the Bottom of Ports and Harbors

Seasonal Variations in Characteristics of Oxygen Consumption by the Bottom of Ports and Harbors

Characteristics of Oxygen Consumption by the Bottom of Port and Harbor under Anoxic Environment

For effective restoration of enclosed coastal zone under anoxic environment such as Osaka bay, it is necessary to understand characteristics of oxygen consumption by the bottom sediment of port and harbor. In this study, in-situ measurement method of oxygen consumption by using a convenient chamber was developed. From results of field investigation particular characteristics of the sediment oxygen demand in port and harbor under anoxic environment were presented.

Development of a Biomimetic Root Oxygen Bioavailability Sensor

Low oxygen availability in soil can impair root function, thereby decreasing agronomic productivity. Without oxygen to support mitochondrial respiration, energy levels in roots may limit mineral nutrient (N, P, K) transport. Traditional methods for measuring soil oxygenation include the use of redox electrodes and polarographic oxygen sensors. These approaches are limited to measuring oxygen concentrations at specific locations and cannot determine the bio-availability of that oxygen to a growing root. An innovative approach has been developed for direct measurement of oxygen bioavailability. Instead of building the sensor to measure oxygen concentrations, it is possible to construct an electrochemical system in a manner that makes it sensitive to changes in oxygen transport and availability in the soil. Furthermore, it is even possible to construct the sensor to match the oxygen consumption characteristics of a specific root tip, which is important because most metabolism and nutrient uptake occurs here. This is accomplished by using a conductive-gel membrane system that allows sensor profiles to be engineered to match the metabolic profiles of specific species. If constructed to these standards, the sensor will biomimetically replicate biophysical oxygen depletion profiles that are analogous to those found in the rhizosphere of a growing root tip. The biomimetic root oxygen bio-availability (ROB) sensor integrates all biotic and abiotic factors in the soil that limit oxygen transport to the root, while providing real-time sensing. This new sensor technology could be used as a research tool or as a closed-loop control system for field and greenhouse irrigation.

Microfluidic chip integrated with amperometric detector array for in situ estimating oxygen consumption characteristics of single bovine embryos

The detection of oxygen consumption as an indicator of the bovine embryo activity has attracted much attention. A microfluidic chip with the built-in amperometric detector array was successfully constructed to transport, immobilize, and in situ measure a single bovine embryo for the evaluation of oxygen consumption characteristics. The microfluidic chip consisted of a poly(dimethylsiloxane) slab containing a size-limited transportation microchannel and a glass substrate with a 4-working-electrode amperometric detector array located on the bottom of a groove. A single embryo could be transported along the groove and be safely immobilized at the gate position of the microchannel due to the size limitation by using the flow rate of 10μl/min. Subsequently, the oxygen consumption characteristics of the embryo were in situ measured with the amperometric detector array. The average value of oxygen concentration difference (ΔC) between the bulk solution and the Day-6 embryo surface based on the analysis of spherical diffusion theory was 2.80±0.72μM at room temperature. Moreover, the correlation coefficient of more than 0.92 indicates that the spherical diffusion theory could be suitable for depicting the oxygen consumption layer of an embryo at the morula stage in the microchannel. The success of the presently used microfluidic chip not only greatly simplifies the expensive instrument requirements such as scanning electrochemical microscope and stereo-positioning manipulator but also makes the transportation, immobilization, and detection of a single embryo feasible within a microchip.

Characteristics of Oxygen Consumption at Exercising Muscle in Patients with Chronic Obstructive Pulmonary Disease

Characteristics of Oxygen Consumption at Exercising Muscle in Patients with Chronic Obstructive Pulmonary Disease

Effect of Arm Cranking Direction on EMG, Kinematic, and Oxygen Consumption Responses

The purpose of this study was to compare muscle activity, kinematic, and oxygen consumption characteristics between forward and reverse arm cranking. Twenty able-bodied men performed 5-min exercise bouts of forward and reverse arm cranking while electromyographic (EMG), kinematic, and oxygen consumption data were collected. EMG activity of biceps brachii, triceps brachii, deltoid, and infraspinatus muscles were recorded and analyzed to reflect on-time durations and amplitudes for each half-cycle (first 180° and second 180° of crank cycle). Kinematic data were quantified from digitization of video images, and oxygen consumption was calculated from expired gases. Dependent measures were analyzed with a MANOVA and follow-up univariate procedures; alpha was set at .01. The biceps brachii, deltoid, and infraspinatus muscles displayed greater on-time durations and amplitudes for select half-cycles of reverse arm cranking compared to forward arm cranking (p< 0.01). Peak wrist flexion was 9% less in reverse arm cranking (p< 0.01), and oxygen consumption values did not differ between conditions (p= 0.25). Although there were no differences in oxygen consumption and only minor differences kinematically, reverse arm cranking requires greater muscle activity from the biceps brachii, deltoid, and infraspinatus muscles. These results may allow clinicians to more effectively choose an arm cranking direction that either minimizes or maximizes upper extremity muscle activity depending on the treatment objectives.

Oxygen Consumption Characteristics of Porcine Hepatocytes

Oxygen uptake rate (OUR) of hepatocytes is an important parameter for the design of bioartificial liver assist (BAL) devices. Porcine hepatocytes were cultured in a specially constructed measurement chamber with an incorporated mixing system and a Clark polarographic oxygen electrode. Signal noise associated with conventional Clark electrode implementations was circumvented by the combination of real time digital numerical averaging and subsequent finite impulse response (FIR) spectral filtering. Additional software allowed for the automated generation of cellular oxygen consumption coefficients, namely,VmaxandK0.5, adding a high degree of objectivity to parameter determination. Optimization of the above numerical techniques identified a 0.1 Hz/200 data point sample size and a 0.004 Hz cutoff frequency as ideal param- eters.Vmaxvalues obtained for porcine hepatocytes during the first two weeks of culture showed a maximal consumption of 0.9 nmole/sec/106cells occurring on Day 4 post seeding, and a gradual decrease to 0.31 nmole/sec/106cells by Day 15.K0.5values increased from 2 mm Hg on Day 2 to 8 mm Hg by Day 8, with gradual subsequent decrease to 4 mm Hg by Day 15. TheVmaxandK0.5values measured for porcine cells were higher than maximal values for rat hepatocytes (Vmax: 0.43 nmole/sec/106cells,K0.5: 5.6 mm Hg) and thus may necessitate significantly altered BAL device design conditions to ensure no oxygen limitations. Finally, these results highlight the need for species specific characterization of cellular function for optimal BAL device implementations.

Arctic sediments (Svalbard): consumption and microdistribution of oxygen

Total sediment oxygen consumption rates (TSOC or J tot), measured during sediment-water incubations, and sediment oxygen microdistributions were studied at 16 stations in the Arctic Ocean (Svalbard area). The oxygen consumption rates ranged between 1.85 and 11.2 mmol m −2 d −1, and oxygen penetrated from 5.0 to ⩾ 59 mm into the investigated sediments. Measured TSOC exceeded the calculated diffusive oxygen fluxes ( J diff) by 1.1–4.8 times. Diffusive fluxes across the sediment-water interface were calculated using the whole measured microprofiles, rather than the linear oxygen gradient in the top sediment layer. The lack of a significant correlation between found abundances of bioirrigating meiofauna and high J tot J diff ratios as well as minor discrepancies in measured TSOC between replicate sediment cores, suggest molecular diffusion, not bioirrigation, to be the most important transport mechanism for oxygen across the sediment-water interface and within these sediments. The high ratios of J tot J diff obtained for some stations were therefore suggested to be caused by topographic factors, i.e. underestimation of the actual sediment surface area when one-dimensional diffusive fluxes were calculated, or sampling artifacts during core recovery from great water depths. Measured TSOC correlated to water depth raised to the −0.4 to −0.5 power (TSOC = water depth −0.4 to −0.5) for all investigated stations, but they could be divided into two groups representing different geographical areas with different sediment oxygen consumption characteristics. The differences in TSOC between the two areas were suggested to reflect hydrographic factors (such as ice coverage and import/production of reactive particulate organic material) related to the dominating water mass (Atlantic or polar) in each of the two areas. The good correlation between TSOC and water depth −0.4 to −0.5 rules out any of the stations investigated to be topographic depressions with pronounced enhanced sediment oxygen consumption.

Oxygen consumption and ATP changes of the vertebrate photoreceptor

The oxygen consumption characteristics of the excised bullfrog retina ( R. catesbeiana ) were studied with a technique that permitted continuous monitoring of the oxygen consumption of the retina at a high sensitivity. In the presence of the (Na + +K + ) ATPase inhibitor, ouabain, or in low [Na + ] 0 ( m ) or low [K + ] 0 ( m ) increases in oxygen consumption are observed upon illumination (designated as the “ouabain respiratory response”). These responses are unquestionably from the photoreceptors and reflect light-induced increases in ATP synthesis. The data on these responses and direct measurements of ATP suggest that they are the result of light-induced ATP consuming processes which cause decreases in the ATP concentration of the photoreceptor. Increases in internal calcium concentration could also be responsible for the response or more likely may be an intermediate step in the processes leading to these responses. In normal perfusate (containing aspartate) decreases in oxygen consumption are observed upon illumination reflecting light-induced decreases in ATP synthesis (designated as the “normal respiratory response”). The data on these responses and direct measurements of ATP concentration suggest that these responses originate in the photoreceptors and reflect light-induced increases in ATP concentration as a result of decreases in (Na + +K + ) ATPase activity. Changes in calcium ion concentration may be an intermediate step in the processes leading to these responses. Both respiratory responses exhibited similar relations between response amplitude and light intensity—a relationship similar to that observed for distal PIII electrical responses of the photoreceptor. Uncouplers of oxidative phosphorylation (in the presence of pyruvate) such as DNP, FCCP and arsenate, stimulated overall respiration and eliminated the respiratory responses. The responses were also eliminated by oligomycin (an inhibitor of oxidative phosphorylation) or cyanide (an inhibitor of electron transport). The addition of ouabain, or low [Na + ] 0 or low [K + ] 0 inhibited overall respiration and revealed the “ouabain respiratory responses”. The restoration of normal [Na + ] 0 or [K + ] 0 to perfusate which contained low concentrations of these ions stimulated overall respiration and restored the “normal respiratory responses”. The amplitudes of the “normal respiratory responses” exhibited a dependence on [Na + ] 0 and [K + ] 0 . In the presence of ouabain these ions had no effect on respiration. Calcium ion was a major effector of overall respiration and the “respiratory responses”. For both respiratory responses increasing the calcium ion concentration (above 0.032 m m ) mimicked the effect of light —i.e. increasing or decreasing overall respiration and reducing the amplitude of the “respiratory responses”.

Analysis of the pattern of energy expenditure of rats in different age periods

A study was carried out of the characteristics of oxygen consumption at different age periods in rats kept in a respiratory chamber at a temperature corresponding to that in their natural habitat. The experiments were carried out on 407 animals. In albino rats the oxygen consumption increases after birth both per unit of weight and per unit of body surface, reaching the maximum at the time of assuming the standing posture (11th–17th day after birth) −104.6 ml/kg weight and 323.6 ml/m2 body surface per minute. During subsequent postnatal development oxygen consumption both per unit of weight and per unit of body surface gradually decreases. At the same time, a progressive decrease in oxygen consumption occurs per unit of body weight up to the adult period, reaching 35.0 ml/kg per min. The oxygen consumption per unit of body surface falls only until one month of age, after which it increases again. It is concluded that change in oxygen consumption reflecting the energy expenditure rate in the postnatal ontogenetic process does not conform to the “surface energy rule”.