Continuous Measurement Of Oxygen Consumption Research Articles

Energy requirements of Holstein, Gyr, and Holstein × Gyr crossbred heifers using the respirometry technique

We aimed to determine the energy requirements for maintenance and gain of 18 prepubertal dairy heifers of three breed compositions (BC; Holstein, Gyr, and Holstein × Gyr). Diets were formulated for gains of 0, 400, and 800 g/day, corresponding to 1.0×, 1.5×, and 2.0× maintenance, respectively. Each dairy BC had six animals with an initial body weight (iBW) of 219.8 ± 32 kg, 215.8 ± 33 kg, and 228.3 ± 33 kg for Holstein, Gyr, and Holstein × Gyr, respectively. The experiment was designed as a completely randomized design in a factorial scheme 3 × 3 [three BC and three feeding levels (FL)]. Digestibility and metabolism assays were performed to determine energy losses through feces and urine. Heat production was determined using the continuous measurement of oxygen consumption, carbon dioxide production, and methane emissions in respiration chambers. Energy requirements for maintenance (NEm) were calculated based on the relationship between heat production (HP) and metabolizable energy intake (MEI). The efficiency of use of metabolizable energy for maintenance (km) was obtained from the ratio between NEm and metabolizable energy requirements for maintenance. The net energy requirements for growth (NEg) were estimated from the model RE = β0 × EBW0.75 × EBGβ1, where RE is the retained energy (Mcal/day), EBW is empty body weight (kg0.75), and EBG is the empty body gain (kg/day). The efficiency of use of metabolizable energy for gain (kg) was estimated as the slope of the regression between RE and MEI for gain. Gyr heifers presented NEm 15% lower (98 kcal/kg of BW0.75) than HG crossbred animals. Holstein and crossbred heifers had similar NEm, 102 and 112 kcal/kg of BW0.75, respectively. The km was 0.71, 0.74, and 0.75 for HG, Holstein, and Gyr, respectively. Net energy requirement for gain (NEg) did not differ across BC, and a single equation was fit for all BC: RE = 0.069 × BW0.75 × BGW0.852. A single kg of 0.65 was observed for all three BC. Breed composition affected the energy requirements for maintenance and the energy partition, and those differences should be considered when estimating requirements for Gyr, Holstein × Gyr crossbred, and Holstein heifers.

The impact of acute bouts of interval and continuous walking on energy-intake and appetite regulation in subjects with type 2 diabetes.

In healthy subjects, it has been suggested that exercise may acutely suppress energy‐intake and appetite, with peak intensity being an important determinant for this effect. In subjects with type 2 diabetes (T2D), the effect of exercise on appetite‐related variables is, however, virtually unknown. We aimed to assess the effects of two exercise interventions, differing with regards to peak intensity, on energy‐intake, satiety and appetite‐related hormones in subjects with T2D. Thirteen subjects with T2D completed three 60‐min interventions with continuous measurement of oxygen consumption in a randomized and counterbalanced order: (1) Control, (2) Continuous walking (CW; intended 73% of VO 2peak), (3) Interval‐walking (IW; repeated cycles of 3 min slow [54% of VO 2peak] and 3 min fast walking [89% of VO 2peak]). Forty‐five minutes after completion of the intervention, a 3‐h liquid mixed meal tolerance test (MMTT, 450 kcal) with regular satiety assessments and blood samples for appetite‐related hormones commenced. An ad libitum meal was served after the MMTT, with subsequent calculation of energy‐intake. Moreover, free‐living diet records were completed for the following ~32 h. Exercise interventions were well‐matched for mean oxygen consumption (CW = 77 ± 2% of VO 2peak; IW = 76 ± 1% of VO 2peak, P > 0.05). No differences in appetite‐related hormones or energy‐intake were found (P > 0.05 for all comparisons). IW increased fullness compared to Control shortly after the intervention (P < 0.05) and tended to reduce hunger 2 h into the MMTT compared to CW and Control (P < 0.10). In conclusion, a single exercise session does not affect energy‐intake during the following ~4–36 h in subjects with T2D. However, satiety may be affected up to ~3 h after the exercise session, dependent on peak intensity.

Significant Enhancement of ATP-Synthesis in Cardiomyocytes By Electric Microcurrent

Full Text Article Outline I. Objective II. Methods III. Results IV. Conclusion Objective The cardiomyocytes of failing hearts show a significant reduced ability to synthesize ATP. On the one hand, the ATP synthesis depends on the level of the H+ based mitochondrial membrane potential which is impaired in heart failure and which in turn correlates to the electron transfer rate of the respiratory chain of the mitochondria. On the other hand, the electron transfer rate can be changed by external electric fields. We thought to examine the effect of electric fields concomitant with low and high electric microcurrent on the capability of mitochondria of cultured cardiomyocytes from spontaneous hypertensive rates to synthesize ATP. Methods Cardiomyocytes of the myocardium of spontaneous hypertensive rats (N=5; 11 weeks old) were stimulated electrically by use of a direct current (dc) power generator via two electrodes under cultured conditions. Of each SHR myocardium, five times three specimens of myocytes were taken, cultured and exposed to the dc with the intensity zero (control), 10 (low) or 100 (high) μA over a period of 72h. Mitochondrial respiration of dc treated cells was measured via the Oxygraph 2K (Oroboros, Innsbruck, Austria). This instrument allows the continuous measurement of oxygen consumption of intact cells. A sequence of the inhibitors oligomycin, carbonyl cyanide4-(trifluoromethoxy)phenylhydrazone and rotenone was added to analyze the impact of different mitochondrial complexes on respiration. ATP of microcurrent treated SHR cardiomyocytes was isolated by an ATP-assay (Abcam, ab83355) and quantified fluorometrically. Article Tools PDF (226 KB) Email Article Add to My Reading List Export Citation Create Citation Alert Cited by in Scopus (0) Request Permissions Order Reprints (100 minimum order) Related Articles All Content Search Advanced Search | Register August 2015 Volume 21, Issue 8, Supplement, Page S19 Karin Macfelda Alexander Holly Johannes Mueller Access this article on ScienceDirect Home Articles & Issues For Authors Journal Info Subscribe Society More Periodicals

Effects of saponin fractions from fenugreek and the soap bark tree in the diet on performance of Nile tilapia, Oreochromis niloticus (L.)

Saponins are generally regarded as anti-nutritional factors in aquaculture diets. However, previous experiments have shown that low dietary levels of saponins derived from Quillaja saponaria Molina do have growth promoting effects on common carp and Nile tilapia. Based on these experiments, we conducted an experiment in which we fed eluated saponin fractions from Q. saponaria and Trigonella foenum-graecum L. (fenugreek) to Nile tilapia in a respirometric system allowing for continuous measurement of oxygen consumption. Saponins were eluated with consecutive methanol/water concentrations (v/v, 40/60, 60/40, 80/20) resulting in three different eluates for each plant. Fractions chosen were the 80% methanol eluate from Q. saponaria (80QS) and all three eluates from T. foenum-graecum (40TS, 60TS and 80TS). Three fish each were fed with low levels (150 mg kg-1 diet) of saponins in the diet and a control diet without saponins. Growth, feed and nutrient utilization, proximate composition, oxygen consumption and metabolic performance were evaluated. The fish grew between 224% (40TS) and 266% (Control) over the eight week period. Feed conversion ratios were between 0.94 (80TS) and 1.15 (40TS) and protein efficiency ratios between 2.54 (80TS) and 2.16 (40TS). Due to low sample sizes, no statistical differences were found between control fish and saponin fed fish. However, numerically one of the tested saponin fractions (40TS) showed inferior performance (Table 1). It is concluded that the tested saponins in the tested concentrations are no potential growth promoter for Nile tilapia. On the contrary, one fraction appears to be a growth inhibitor.

A Field Evaluation of the Physiological Demands of Miners in Canada's Deep Mechanized Mines

This study was conducted to evaluate the physical/mechanical characteristics of typical selected mining tasks and the energy expenditure required for their performance. The study comprised two phases designed to monitor and record the typical activities that miners perform and to measure the metabolic energy expenditure and thermal responses during the performance of these activities under a non-heat stress environmental condition (ambient air temperature of 25.8°C and 61% relative humidity with a wet bulb globe temperature (WBGT) of 22.0°C). Six common mining jobs were evaluated in 36 miners: (1) production drilling (jumbo drill) (n = 3), (2) production ore transportation (load-haul dump vehicle) (n = 4), (3) manual bolting (n = 9), (4) manual shotcrete (wet/dry) (n = 3), (5) general services (n = 8) and, (6) conventional mining (long-hole drill) (n = 9). The time/motion analysis involved the on-site monitoring, video recording, and mechanical characterization of the different jobs. During the second trial, continuous measurement of oxygen consumption was performed with a portable metabolic system. Core (ingestible capsule) and skin temperatures (dermal patches) were recorded continuously using a wireless integrated physiological monitoring system. We found that general services and manual bolting demonstrated the highest mean energy expenditure (331 ± 98 and 290 ± 95 W, respectively) as well as the highest peak work rates (513 and 529 W, respectively). In contrast, the lowest mean rate of energy expenditure was measured in conventional mining (221 ± 44 W) and manual shotcrete (187 ± 77 W) with a corresponding peak rate of 295 and 276 W, respectively. The low rate of energy expenditure recorded for manual shotcrete was paralleled by the lowest work to rest ratio (1.8:1). While we found that production drilling had a moderate rate of energy expenditure (271 ± 11 W), it was associated with the highest work to rest ratio (6.7:1) Despite the large inter-variability in energy expenditure and work intervals among jobs, only small differences in average core temperature (average ranged between 37.20 ± 0.22 to 37.42 ± 0.18°C) were measured. We found a high level of variability in the duration and intensity of tasks performed within each mining job. This was paralleled by a large variation in the work to rest allocation and mean energy expenditure over the course of the work shift.

Cellular Uptake, Cytotoxicity, and Metabolic Profiling of Human Cancer Cells Treated with Ruthenium(II) Polypyridyl Complexes [Ru(bpy)2(NN)]Cl2 with NN=bpy, phen, dpq, dppz, and dppn

A series of five ruthenium(II) polypyridyl complexes [Ru(bpy)2(N--N)]Cl2 was tested against human HT-29 and MCF-7 cancer cell lines. Cellular uptake efficiency and cytotoxicity were found to increase with the size of the aromatic surface area of the N--N ligand. The most active compound carrying the dppn ligand exhibits a low micromolar IC(50) value against both cell lines comparable to that of cisplatin under similar conditions. Continuous measurement of oxygen consumption, extracellular acidification rate, and impedance of the cell layer with a chip-based sensor system upon exposure to the complexes showed only small changes for the first two parameters throughout the series. A significant and irreversible decrease in impedance was, however, found for the dppn compound. This suggests that its biological activity is related to modifications in cell morphology or cell-cell and cell-matrix contacts.

Influence of aeration rate and biodegradability fractionation on composting kinetics

The influences of aeration rate and biodegradability fractionation on biodegradation kinetics during composting were studied. The first step was the design of a suitable lab-reactor that enabled the simulation of composting. The second step comprised of composting trials of six blends of sludge (originating from a food processing effluent) with wood chips using aeration rates of 1.69, 3.62, 3.25, 8.48, 11.98 and 16.63 L/h/kg DM of mixture. Biodegradation was evaluated by respiration measurements and from the analysis of the substrate (dry matter, organic matter, total carbon and chemical oxygen demand removal). Continuous measurement of oxygen consumption was coupled with the analysis of initial substrate and composted product for chemical oxygen demand (in the soluble and non-soluble fractions), which enabled an evaluation of the organic matter biodegradability. Oxygen requirements to remove both the easily and slowly biodegradable fractions were determined. Dividing the substrate into different parts according to biodegradability allowed explanation of the influence of aeration rate on stabilization kinetics. Considering that the biodegradation kinetics were of the first-order, the kinetic constants of the easily and slowly biodegradable fractions were calculated as a function of temperature. The methodology presented here allows the comparison of organic wastes in terms of their content of easily and slowly biodegradable fractions and the respective biodegradation kinetics.

Alteraciones en la tasa de respiración de Daphnia magna bajo concentraciones subletales de anatoxina-a.

Anatoxin-a is a potent neurotoxin produced by some freshwater cyanobacteria which, because of its acute toxic effects, may represent a hazard to aquatic organisms, and even to human beings. Both the acute and chronic effects of this toxin are rather well known, but few studies provided information about its sublethal effect on the zooplankton respiration. In this paper we have quantified respiration changes in Daphnia magna under sublethal anatoxin-a concentrations in experimental conditions, using an automatic open-flow system of continuous measurement of oxygen consumption. Our results show that the presence of anatoxin-a at sublethal doses reduces significantly the respiratory activity of the animals, being the effects greatly dependent on the individual age.

Continuous measurement of oxygen consumption during cardiopulmonary bypass: description of the method and in vivo observations

Background Systemic oxygen consumption is not routinely measured during cardiopulmonary bypass, despite its potential benefits. We aimed to develop a noninvasive method to continuously measure oxygen consumption using respiratory mass spectrometry during hypothermic cardiopulmonary bypass in pigs. Methods Nine pigs weighing 18.5 (1.6) kg underwent hypothermic (32°C) cardiopulmonary bypass for 180 minutes with 120 minutes of aortic cross clamping. An AMIS 2000 mass spectrometer (Innovision A/S, Odense, Denmark) was adapted for the on-line measurement of oxygen consumption by sampling the inlet and outlet gases of the membrane oxygenator together with measurement of the “expired” gas volume. Results Active cooling for 60 minutes reduced the venous blood temperature by 2.9 (0.8) °C and VO 2 by 0.70 (0.33) mL/kg/min. The 40-minute active rewarming restored the venous blood temperature by 4.4 (0.4) °C and oxygen consumption increased by 1.36 (0.33) mL/kg/min. There was wide interanimal variability, however, particularly at higher venous blood temperatures. Immediately after the release of aortic cross clamp, there was a noticeably acute increase in oxygen consumption in all the pigs (0.64 [0.21] mL/kg/min). Conclusions A simple and safe adaptation of mass spectrometry allows continuous measurement of oxygen consumption during hypothermic cardiopulmonary bypass. The wide interindividual variations observed in this pilot study underscore the need to more accurately describe changes in oxygen consumption and how they are affected by temperature, oxygen delivery, and other interventions during cardiopulmonary bypass. As such, the technique may have an important role in clinical research and management of oxygen transport in patients undergoing cardiac surgery.

Continuous measurement of oxygen consumption by pancreatic islets.

The rate of oxygen consumption is an important measure of mitochondrial function in all aerobic cells. In pancreatic beta cells, it is linked to the transduction mechanism that mediates glucose-stimulated insulin secretion. However, measurement of oxygen consumption over long periods of time is technically difficult owing to the error resulting from baseline drift and the challenge of measuring small changes in oxygen tension. We have adapted an ultrastable oxygen sensor based on the detection of the decay of the phosphorescent emission from an oxygen-sensitive dye to a previously developed islet flow culture system. The drift of the sensor is approximately 0.3%/24 h, allowing for the continuous measurement of oxygen consumption by 300 islets (or about 6 x 10(5) cells) for hours or days. Rat islets placed in the perifusion chamber for 24 h were well maintained as reflected by membrane integrity, insulin secretion, and oxygen consumption. Both acute changes in oxygen consumption as induced by glucose and chronic changes as induced by sequential pulses of azide were resolved. The features of the flow culture system--aseptic conditions, fine temporal control of the composition of the media, and the collection of outflow fractions for measurement of insulin, and other products--facilitate a systematic approach to assessing metabolic and functional viability in responses to a variety of stimuli. Applications to the measurement of effects of hypoxia on insulin secretion, membrane integrity, and the redox state of cytochromes are demonstrated. The system has particular application to the field of human islet transplantation, where assessment and the study of islet viability have been hampered by a lack of experimental methods.

Dietary supplementation with a Quillaja saponin mixture improves growth performance and metabolic efficiency in common carp ( Cyprinus carpio L.)

The effects of supplementation of a saponin mixture in diets of common carp were studied using a respirometer system, which allowed feeding and continuous measurement of oxygen consumption of individual fish. Five fish, each weighing approximately 19 g, were fed either a normal diet (C group) or a diet supplemented with 150 mg kg −1 (S150 group) or 300 mg kg −1 (S300 group) Quillaja saponins. At the end of the experimental period (8 weeks), the weight gain of the S150 group (372%) was significantly ( P<0.05) higher than that of the control group (327%) and that of the S300 group (325%), which was similar to the control group. The average metabolic rate (mg kg −0.8 h −1) and oxygen consumption per unit body weight did not differ among the groups. For up to 4 weeks, the average feed conversion ratio and metabolic growth rate values of the S150 group were significantly ( P<0.05) better than those of the C group. Later, the differences narrowed and were no longer significant at the end of the experiment. The average protein utilisation values at the end of the experiment were highest in the S150 group. The S150 group also had the highest average energy retention value. The average apparently unutilised energy was lowest for the S300 group. It is concluded that Quillaja saponin mixture could act as a growth stimulant for common carp when present at a level of 150 mg kg −1 in the diet.

Effects of Quillaja saponins on growth, metabolism, egg production and muscle cholesterol in individually reared Nile tilapia ( Oreochromis niloticus)

The effects of supplementation of a Quillaja saponin (QS) mixture in the diets of tilapia have been studied using a respirometer system that allowed feeding and continuous measurement of oxygen consumption of individual fish. Five fish each were given control diet (C group) and control diet supplemented with 150 mg kg −1 (S150 group) or 300 mg kg −1 (S300 group) QS. At the end of 14 weeks the weight gain of the S300 group was significantly higher than control ( P<0.05) whereas that of the S150 group had an intermediate value. The S150 group had a higher growth rate ( P=0.05) after the first 3 weeks of feeding with the experimental diets, compared to the other two groups. At the end of the experiment the S300 group had significantly higher ( P<0.05) average values for energy retention, apparent lipid conversion, carcass fat, energy and significantly lower ( P<0.05) average values for apparently unutilised energy and carcass ash content compared to the C group. The corresponding values of the S150 group were intermediate between the C and S300 groups. One out of two female fish in the S150 group and both female fish in the S300 group never produced eggs during the entire 14-week experimental period. Contrarily, all three female fish in the control group and one out of the two female fish in the S150 group regularly produced eggs, at a rate of approximately once in every 14 days. The muscle cholesterol level in the S300 group was significantly higher than that of the C group. Possible mechanisms of action of the dietary saponins are discussed.

Effects of cyclic and regular feeding of a Quillaja saponin supplemented diet on growth and metabolism of common carp (Cyprinus carpio L.)

Fifteen common carp weighing 19.2±2.9 g were reared individually in chambers of a respirometer system which allowed feeding, and continuous measurement of oxygen consumption. The fish were divided into three groups of 5 each, and were given control feed (C group), control feed supplemented with 150 mg kg−1 of Quillaja saponins (QS) (S150 group), and control and the saponin supplemented diet during alternate weeks (S150b group), for 56 days. Supplementation with QS at a level of 150 mg kg−1 caused a significant (P<0.05) increase in metabolic growth rate, food conversion efficiency (FCE), protein productive value (PPV) and apparent lipid conversion (ALC) of carp, even as the metabolic rate was lower than the C group. The efficiency of energy utilisation indicated by parameters such as energy expenditure (EE), energy retention (ER) and amount of oxygen consumed per unit body mass gain (OPM) were also significantly (P<0.05) better in the S150 group. The performance of the S150b group was intermediate between the C and S150 group in this experiment. Possible reasons for the effects of dietary QS are discussed. It was concluded that there has to be continuous dietary supply of QS at the level of 150 mg kg−1, for maximum positive effects of these substances on growth of common carp.

Continuous measurement of oxygen consumption using the reversed fick method.

We developed a continuous oxygen consumption (Vo2) measurement system employed the reversed Fick method, in which Vo2 in computed from continuously measured sured arterial and mixed venous oxygen saturation assed by pulse oximetry and mixed venous oximetry, respectively, and cardiac output by the heat deprivation technique. This system was compared with the conventional intermittent reversed fick method in 7 patients during surgery and with indirect calorimetry in 4 intensive care unit (ICU) patients. The Vo2 measured by the continuous reversed Fick method showed a high correlation with those simultaneously measured by the intermittent Fick method (r=0.97,P<0.01) and by indirect calorimetry (r=0.74,P<0.01). The 95% confidence limits (bias±2 SD) of the continuous reversed Fick method were -0.6±45 ml·min-1 with the intermittent Fick method and -31±56 ml·min-1 with indirect calorimetry. The continuous Fick method is in satisfactory agreement with the conventional methods for the measured of Vo2 and potentially allows for convenient assessment of Vo2 in critically ill patients.

Continuous measurement of oxygen consumption using the reversed Fick method

Continuous measurement of oxygen consumption using the reversed Fick method

A new procedure for the continuous measurement of oxygen consumption in pigs

SUMMARYWhole-body oxygen (O2) consumption was measured continuously in pigs from the product of blood flow through the pulmonary artery and arterio-venous (AV) difference of blood O2 content across the lungs (pulmonary AV procedure). Blood flow in the pulmonary artery, a measure of cardiac output, was monitored continuously using a transit-time ultrasound flow probe surgically implanted around the artery. The O2 content of pulmonary artery blood, which represents mixed venous blood O2 aturation (SvO2) was recorded continuously by fibre-optic oximetry. The relative constancy of arterial blood oxygen saturation (SaO2), obtained by catheterization of the saphenous artery, obviated the need for continuous monitoring. Complete recovery from surgical procedures, as indicated by the absence of infection and a return to pre-surgery food intake, occurred in 3–5 days. The combination of transit-time ultrasound and fibre-optic oximetry allowed the pulmonary AV procedure to provide continuous data on the oxygen consumption of growing pigs at high temperatures.

The influence of gradual water acidification on the oxygen consumption pattern of fish

1. Carp ( Cyprinus carpio) and tilapia ( Oreochromis mossambicus) were kept in a flow-through respirometer for a week, while continuous oxygen consumption measurements were carried out, at a constant water O 2 concentration. 2. Our measurements showed that tilapia decreased its standard metabolic rate (SMR), its average oxygen consumption, and its maximum metabolic rate in acid water (pH 4.0), whereas carp did not. 3. It is proposed, based on our results, that carp and tilapia probably have different strategies to survive pH depression episodes: whereas tilapia avoids the additional stress of exercise, carp tries to escape the acid conditions.

A system for measuring phytoplankton photosynthesis in a defined light field with an oxygen electrode

A system is described for the precise continuous measurement of oxygen consumption and photo-synthetic oxygen evolution in a well defined light field with a polarographic oxygen electrode. The procedure uses a parallel light beam to irradiate samples, a relatively short pathlength and temperature regulation. Maximal sensitivity of the O 2 -mcasurement is 1.4 μmol O 2 /mV at 20°C. The O 2 -chamber and the O 2 -amplifier are presented in full detail together with a typical recorder tracing of a photosynthesis-irradiance curve.

Effects of a Thermal Ceiling on Postoperative Hypothermia

Moderate per- and postoperative hypothermia initiates an increased metabolism in the postoperative period. The subsequent demands on oxygen transport may be critical in poor risk patients. Nineteen healthy young women with moderate hypothermia after abdominal surgery were studied for 2 h postoperatively with or without external heating from a heating ceiling. Central and peripheral temperatures, oxygen consumption, plasma catecholamines and shivering were measured. A method for continuous measurement of oxygen consumption and carbon dioxide production during spontaneous breathing is described. The results suggest that postoperative external heating decreases oxygen consumption, shivering and plasma catecholamine levels. At the same time, the comfort of the patient is increased considerably.

Continuous measurement of oxygen consumption in fetal sheep

A microcomputer-based system has been developed to measure oxygen consumption continuously in fetal sheep. The system includes an umbilical artery electromagnetic blood flow transducer and two fiberoptic catheter oximeters for measuring umbilical artery and vein oxyhemoglobin saturation in vivo. The electrical signals from these instruments are digitized and sampled by a microcomputer. Fetal oxygen consumption is calculated from the Fick principle by use of the digitized signals and hemoglobin concentrations. The latter is measured intermittently and updated if necessary. System validation required that artifacts in oxyhemoglobin recordings could be avoided and that the catheter readings agreed with values from intermittent samples. Continuous heparin infusion and careful catheter placement facilitated attainment of these requirements. The system can be used to obtain continuous recordings of fetal oxygen consumption during rapidly occurring physiologic events.