Oxygen consumption, measurement

Figure 5. Oxygen consumption measurements of tumor lung tissue before and after exposure to an atmospheric Rn-d concentration of 6 WL unirradiated control tissue at the beginning of the...

C. Huggett, Estimation of rate of heat release by means of oxygen consumption measurements. Fire... 

FIGURE 5>19 Data from oxygen consumption measurements and RQ calculations can be used to determine the internal energy fuels being used. 

Rate of oxygen consumption measured after 2 hours of reaction. 

In man, Barr et al. (B5) have reported very favorable results in treating burns by blowing dry air at 32°C over the patients. Oxygen consumption measurements indicated a reduction in the anticipated phase of increased general metabolism. The patients general nutrition remained good. 

Any recording spectrophotometer or spectralline photometer is suitable for oxygen consumption measurements if meets three important requirements (1) high monochromator resolution (2) sensitivity and (3) stability. Since hemoglobin derivatives have rather narrow absorption bands in the visible spectrum, a perfect calibration of the monochromator is necessary. Spectral-line photometers using low-pressure mercury lamps in conjunction with appropriate interference filters are well suited for utilization of the Hb02 method, as there are three different filters for the... 

Figure 3. Mixing attachment (right) and electronic board for power supply (left) for oxygen consumption measurements adaptable to Eppendorf spectralline photometers (a) changeable cuvette holder thermostatable with separate thermostat (b) cover of the photomultiplier tube (c) motor set for magnetic stirrer (d) switch for power supply (e) potentiometer for stirring frequency (15-1800 rpm).

In this way the sensitivity of oxygen consumption measurements is increased, that is, 1 mole of oxidized substrate corresponds to 1 mole of oxygen taken up. When catalase is added in absence of a hydrogen donor, 1 mole of the oxidized substrate corresponds to 2 mole of oxygen (Table IV). 

Chambers for oxygen consumption measurements are prepared from microscopic slides coated with a thin paraffin film. With a tip of a hypodermic needle held in a micromanipulator, a small round dent of 10—15 pm is made in the paraffin film, and a drop of 40% HF applied to the dent enables the formation of small circular cavities visible after the removal of paraffin. To increase the measuring capacity, an automatic cuvettechanging device has been developed. The object stage maintained at constant temperature by water circulation from a temperature controlled bath, is moved in six discrete steps by a synchronous motor. Thus, oxygen consumption in six different chambers can be assayed simultaneously. The basic equipment used for microspectrophotometric determinations of oxygen consumption does not differ essentially from the equipment used for other purposes, such as cytophotometry (Hamberger et al., 1975). 

Oxygen consumption measurements in intact cells. Methacrylic monomers - unlike ATRA - cause a significant reduction of oxygen consumption rate by cells (p<0.05) (Fig. 3). 

If A02 (growth) and AOa (decay) are sufficiently large to be accurately measured, then the ratio kp/2kt is easily obtained and with a value of kp/ (2fet)1/2 from direct, initiated oxidation, yields kp and kt separately. The limiting factor on this method is the sensitivity of the oxygen consumption measurement. If a pressure detector can detect 2 X 10 3 torr, kp/2kt must be greater than 10-8 to be measured with a precision greater than... 

Oxygen consumption measurements [56-58] suggest distinct oxidation reactions for ferritin ferroxidase and mineralization processes. For the recombinant human and frog H ferritins, ferroxidase activity dominates with low iron loading (less than 50 Fe/ferritin 24-mer) and a Fe/Oa ratio of 2 is observed with H2O2 being the principle reduction product. The catalytic reaction was suggested to follow Eq. (16.3). 

If only a "yes-no" answer Is sufficient, a combination of (1) oxygen-consumption measurements, and (11) analysis of concentration of acceptor A decrease, or AO2 formation (events 1 and 11 can be measured simultaneously) In the absence and In the presence of a compound Q for a given time of constant Irradiation t, completed with (111) oxygenation(s) of A In the presence and In absence of Q with chemically or by microwave discharge generated IO2 should be carried out. In most cases these three simple experiments can either discover side-reaction paths of 02 AO2, or Q, respectively, or deliver quite a reliable "yes-no" answer (79). Providing that no complications occur, reasonable relative quenching efficiencies related to some known quencher Q (Tables 2-11) can be very easily obtained In this way. 

Substrates 2-aminofluorene, N,N-dimethylaniline, methimazole, phenylhydrazine and 1,1-dimethylhydrazine (substrate-stimulated oxygen consumption measured). 

Fig. 10.9. Lipid peroxidation of egg PC liposome systems containing different fatty acids. Oxygen consumption measured in a closed chamber with test samples of A) 5 mol% of PC(SA LA) in egg PC B) egg PC C) 5 mol% PC(SA f10,c12-CLA) in egg PC and D) 5 mol% PC(SA c9,f11-CLA) in egg PC liposome suspensions (30 mg/mL) at 37°C in 25 mM hepes buffer (pH 7.2) containing CTPO (0.14 mM). Aliquots were taken for ESR determination from the (aerated) reaction mixture that had been incubated at 37°C for 45 min.

Dinitrophenol is an inhibitor of oxidative phosphorylation. Mitochondria isolated from the lungs of rats kept at 85 2% O2 for 7 days, when treated with 0.5 mM 2,4-dinitrophenol, in the presence of 1 mM CN" were maximally uncoupled, since state 3U respiration in the presence of 2,4-dinitrophenol was identical to the mitochondria oxygen consumption measured after ADP addition when 2,4-dinitrophenol was absent (Freeman and Crapo 1981). 

While the choice of calibration method depends upon the reagents available and the specific application of each worker, it must be emphasized that calibration should not be overlooked since the monitor in itself is relative and must be related to actual oxygen concentrations (activities) in order to render any but the most qualitative oxygen consumption measurements meaningful. 

A) Oxygen Consumption Measurement. In the present study, PI values calculated using oxygen consumption measurements were used as a reliable chemical measure for... 

For each mole of ATP which is formed, 1 mole of glucose-6-phosphate is produced, and 1 mole of inorganic phosphate disappears. It is thus possible to measure the uptake of inorganic phosphate in isolated enzyme systems which are carrying out oxidative phosphorylations, and to correlate this phosphate uptake with oxygen consumption measured simultaneously in the... 

Gillen KT, Bernstein R, Qough RL, Celina M. Lifetime predictions for semi-crystalline cable insulation materials 1. Mechanical properties and oxygen consumption measurements on EPR materials. Polym Degrad Stab 2006 91 2146-56. 

Results of in-pile tests with Zircaloy-2 and zirconium. The results of autoclave experiments have demonstrated that the corrosion rate of Zircaloy-2 under irradiation at a given set of exposure conditions does not change vith the time of exposure, in contrast to out-of-pile behavior. Two in-pile autoclave experiments, H-57 and H-58, plotted in Fig. 5-15, illastrate this [51]. The lines through the plotted points for tests under radiation exhibit a slope of 1, and those for out-of-pile experiments, a slope of about 0.4. Ill both cases the values for penetration are those calculated from the results of oxygen consumption measurements. It was assumed in the calculations that corrosion of the exposed surfaces in the autoclave... 

Congestive heart failure (CHF) due to ischemic heart disease is a very common clinical situation, particularly in the elderly group of patients. It is however unclear how the myocardial cells behave metabolically when decreased blood flow in the myocardial tissue develops as a result of stenosis, or obstruction of coronary vessels, eventually leading to myocardial infarction. Myocardial metabolism was studied by microcalorimetry and oxygen consumption measurement in tissue from rats with CHF after a myocardial infarction, induced by ligation of the left coronary artery [89]. 

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