Relation between volume change and pressure change in oxygen uptake study using Warburg apparatus.

Taking oxygen and air as gaseous media oxygen uptake study was carried out recording delta V and corresponding delta P. From these data the quantity of oxygen consumed was calculated. It was concluded that delta V x vessel sensitivity x 2 = delta P x vessel constant. Recording of volume change in oxygen uptake study has been advocated.     

Effect of anthracyclines and mitoxantrone on oxygen uptake and ATP intracellular concentration in rat heart slices

The clinical use of anthracycline antibiotics is severely limited by dose-dependent cardiotoxicity. This accounts for our interest in differences on respiratory control of cardiac cells induced by two new anticancer agents epirubicin and mitoxantrone. Cellular oxygen uptake was measured for increasing drugs concentrations with a Warburg manometric apparatus and intracellular ATP by high-pressure liquid chromatography in rat heart slices incubated for 60′ with anthracyclines or mitoxantrone. Epirubicin inhibits endogenous respiration by 18% versus control while doxorubicin and mitoxantrone reduce oxygen uptake by 34 and 46%, respectively. ATP intracellular concentration was significantly reduced by all anticancer agents but particularly by mitoxantrone 86%.These results may be related to the biochemical side effects produced by these drugs on bioenergetics and cellular respiratory control.     

Factors affecting the respiration of rabbit sperm measured with an oxygen electrode

The respiration of rabbit sperm was measured by a Clarke type electrode which has two advantages over the conventional Warburg technique, greater sensitivity, and no necessity for a carbon dioxide-free atmosphere. It was not necessary to resaturate the sample chamber of the oxygen monitor with air, down to about 30% desaturation.Rabbit seminal plasma had a measurable oxygen uptake (0.6 μl/hr/ml) but this was much less than for human seminal plasma (4.3 μl/hr/ml). Hoderate dilution of the sperm and storing the semen at 0°C after slow cooling had no effect on oxygen uptake. Unlike those of most other species, rabbit sperm were also little affected by deliberate exposure to cold shock and the respiration before and after rapid cooling to 0°C was about the same. On the other hand very brief exposure of rabbit sperm to 65°C abolished motility and greatly reduced the respiration rate. Bicarbonate (6 mM) stimulated the oxygen uptake of freshly collected samples of rabbit sperm after washing. Increasing the phosphate concentration of the medium to 80 mM did not greatly depress the oxygen uptake.     

A two-phase oxygen uptake model of aerobic fermentations

The mechanism of Solid particle flotation was used for explaining an alternative route of oxygen uptake by cells situated within the relatively stagnant liquid region adjacent to bubbles in a submerged culture. The Two-phase model of oxygen uptake takes into consideration uptake from both liquid and gaseous phases, the latter being denoted as the direct uptake. Experiments obtained with yeast cultures on different substrates were used to evaluate the proportion of both types of uptake. The combined model provides a better fit to experimental data compared to the one-phase model which omits the direct uptake. The results are discussed from the viewpoint of the enhancement of oxygen absorption by cells present near the interface.     

常压低氧小鼠氧耗量测定新装置的研究及应用

目的：建立一种实时记录常压低氧环境中动物氧耗量的方法。方法：本实验装置由动物舱、补水控制系统、天平、软管、装有体重记录软件的电脑等组成。为了实现常压低氧,用水补充动物消耗的氧气以保持动物舱内压力恒定,这个过程由气液联动装置控制;补充的水量由天平测量并同步输出信号至excel文档中。用注射器抽气校准方法检测了装置的准确性和精度。利用该装置观察了6只急性重复低氧小鼠（处理组）和6只未经低氧处理的小鼠（对照组）的常压低氧过程的氧耗量特征。结果：不同体积抽气量与相应补水量两组数据配对t检验P=1;重复抽1 ml氧气6次的补水量变异系数为4%。处理组小鼠的存活时间为（58.8±6.8）min,显著高于对照组（46.0±8.7）min（P〈0.05）。处理组小鼠的总氧耗量为（85.1±8.5）ml,显著高于对照组（73.6±5.4）ml（P〈0.05）。结论：处理组小鼠摄取氧总量增多从而显著延长其存活时间。氧耗量测定装置准确度和精密度较高,可用于低氧研究中氧耗量的测定。     

Possible use of the oxygen uptake rate in the evaluation of BCG vaccines.

Two existing methods suitable for the determination of the oxygen uptake rate (OUR) in BCG suspensions (Warburg and Gilson Oxygraph) are described and compared. With the former method the oxygen uptake rates of the 10 samples of the BCG collaborative assay of the BCG Steering Committee of the International Association of Biological Standardization were determined. When the results are compared with those of colony count and skin reactivity from the collaborative assay, there is a better correlation between OUR and skin reactivity than between OUR and colony count. From the results of our study there is a strong indication that the OUR is a good parameter for quality, and most probably better suited for interlaboratory comparisons than the colony count.     

Parallel assay of oxygen equilibria of hemoglobin

Methods to systematically analyze in parallel the function of multiple protein or cell samples in vivo or ex vivo (i.e., functional proteomics) in a controlled gaseous environment have so far been limited. Here, we describe an apparatus and procedure that enables, for the first time, parallel assay of oxygen equilibria in multiple samples. Using this apparatus, numerous simultaneous oxygen equilibrium curves (OECs) can be obtained under truly identical conditions from blood cell samples or purified hemoglobins (Hbs). We suggest that the ability to obtain these parallel datasets under identical conditions can be of immense value both to biomedical researchers and clinicians who wish to monitor blood health and to physiologists who are studying nonhuman organisms and the effects of climate change on these organisms. Parallel monitoring techniques are essential in order to better understand the functions of critical cellular proteins. The procedure can be applied to human studies, where an OEC can be analyzed in light of an individual’s entire genome. Here, we analyzed intraerythrocytic Hb, a protein that operates at the organism’s environmental interface and then comes into close contact with virtually all of the organism’s cells. The apparatus is scalable and establishes a functional proteomic screen that can be correlated with genomic information on the same individuals. This new method is expected to accelerate our general understanding of protein function, an increasingly challenging objective as advances in proteomic and genomic throughput outpace the ability to study proteins’ functional properties.     

Enzymatic Degradation of Lignin

Oxidation of homogentisic acid and gentisic acid by the enzyme of Poria subacida and the effect of α,α′-dipyridyl on their oxidation were studied through oxygen uptake using Warburg apparatus. The oxidation products of these two acids were investigated by their ultraviolet absorption spectra and by paperchromatography.     

Batch kinetics and oxygen consumption ofCandida lipolytica 4-1 onn-alkanes

Detailed batch kinetics ofCandida lipolytica 4-1 onn-hexadecane for varying dispersed phase volume from 0.5 to 5% v/v is presented. All batch growth curves exhibited a linear growth region, indicating a substrate uptake limit. System productivities derived from the linear region were correlated to the dispersed phase volume. The correlation coefficient was identical with that obtained on gas oil. This implies that a correlation coefficient of interfacial area to the dispersed phase volume is identical for both systems. Dissolved oxygen profile and uptake of oxygen from gas phase were also measured. The oxygen uptake rate, volumetric oxygen transfer rate and oxygen demand (requirement) were calculated by means of the balance method. Under limiting dissolved oxygen concentration the maximal oxygen transfer of the fermenter was assessed.     

Appetitive response of the nematodeCaenorhabditis elegans to oxygen

Summary Using a technique of recording the behavior of individual nematodes during exposure to various solutions, it was demonstrated thatC. elegans made more reversal behaviors after transfer to solutions of lower oxygen tension than higher. The response was stronger after the first hour in the apparatus than initially. This change was not dependent on reduced oxygen availability during the initial period. Starvation is the most likely cause of this change. A variety of mutant strains ofC. elegans that are defective in response to most known chemotactic stimuli, including two strains that have been shown to be severely abnormal in the ciliated endings of all sensory neurons of the worm's snout, all responded to changes in oxygen tension. This observation suggests that oxygen is sensed internally rather than by specialized peripheral receptor cells.I thank Deborah Higgins for technical assistance. This work was supported by a grant awarded by the Biomedical Research Support Grant Program of the National Institutes of Health.     

Increases in human sperm oxygen consumption at low cell concentrations

Human spermatozoan oxygen consumption was measured in semen serially diluted with its own plasma, and shortly after serial dilution of washed spermatozoa in an artificial medium. In both media, per-sperm oxygen uptake rose significantly when sperm concentration fell below the range of 15-25 X 10(6) cells/ml. Oxygen uptake was higher in the artificial medium, regardless of sperm concentration. Sperm oxygen consumption in the artificial medium declined over times short enough that no change in the percentage of motile spermatozoa was detected.     

Effects of dilution on dissolved oxygen depletion and microbial populations in the biochemical oxygen demand determination

The biochemical oxygen demand (BOD) value is still a key parameter that can determine the level of organics, particularly the content of biodegradable organics in water. In this work, the effects of sample dilution, which should be done inevitably to get appropriate dissolved oxygen (DO) depletion, on the measurement of 5-day BOD (BOD₅), was investigated with and without seeding using natural and synthetic water. The dilution effects were also evaluated for water samples taken in different seasons such as summer and winter because water temperature can cause a change in the types of microbial species, thus leading to different oxygen depletion profiles during BOD testing. The predation phenomenon between microbial cells was found to be dependent on the inorganic nutrients and carbon sources, showing a change in cell populations according to cell size after 5-day incubation. The dilution of water samples for BOD determination was linked to changes in the environment for microbial growth such as nutrition. The predation phenomenon between microbial cells was more important with less dilution. BOD₅ increased with the specific amount of inorganic nutrient per microbial mass when the natural water was diluted. When seeding was done for synthetic water samples, the seed volume also affected BOD due to the rate of organic uptake by microbes. BOD₅ increased with the specific bacterial population per organic source supplied at the beginning of BOD measurement. For more accurate BOD measurements, specific guidelines on dilution should be established.     

Effect of ascorbate on oxygen uptake and growth of Escherichia coli B

The addition of ascorbate to aerobically growing cultures of Escherichia coli B caused only a short pause in growth and no subsequent change in the rate or extent of growth. The effect of ascorbate on oxygen uptake varied from inhibition in minimal medium to stimulation in rich medium. Cyanide-resistant growth and oxygen uptake were stimulated by ascorbate. Both the rate and extent of anaerobic growth were stimulated in proportion to the amount of ascorbate added when fumarate was the terminal electron acceptor. Ascorbate had no effect on any aspect of anaerobic growth in the absence of a terminal electron acceptor or in the presence of nitrate.     

Anticancer susceptibility test method using general-purpose dissolved oxygen meter

Drug susceptibility of cell can be rapidly measured by continuously monitoring its metabolic changes. We focused on respiration volume as a signal of metabolic change, and developed a new dissolved oxygen measuring system which can detect respiration volume of cells. The main feature of the system is the use of a new type bare oxygen electrode which can easily detect the changing rate of dissolved oxygen concentration. In this study, single type electrode was used to evaluate this rapid anticancer drug susceptibility test. The result obtained was almost equivalent to that with MTT method, which is a conventional method for susceptibility test of HL-60 to various kinds of anticancer drugs. We have also developed multi-type electrode plate with oxygen electrodes embedded in the bottom of 96-well plate, with which clinical evaluation of this method can be easily made.     

Influence of moisture and aeration on oxygen uptakes in Warburg respiratory experiments with litter and soil

Summary Oxygen uptakes by litter and soil from a beech forest were determined in a Warburg apparatus, using material at field moisture content, at 60 per cent water-holding capacity (WHC), and at saturation (>100 per cent WHC), in unshaken and shaken flasks. In unshaken flasks, oxygen uptakes by materials from some horizons were markedly dependent upon their moisture content. Oxygen uptakes were similar with unshaken materials at 60 per cent WHC and with shaken water-saturated materials; this latter method of determination is preferred for routinely measuring respiratory activity under aerobic conditions. Control of moisture content of the systems appeared necessary to estimate respiratory responses to added solutions of glucose. Significant responses to added glucose were found with materials from all horizons under conditions of adequate moisture and aeration but responses were much less with some unshaken water-saturated materials.     

A low cost apparatus for the automatic determination of precise oxygen equilibrium curves on red blood cell suspensions

An apparatus for the automatic recording of precise oxygen equilibrium curves on red cell suspensions, as well as on hemoglobin solutions, is described. Dual wavelength determination of fractional oxygen saturation is used, eliminating noise for turbid samples and very small blood samples are needed. An example of data is given for trout blood.     

Limitations to oxygen diffusion and equilibration in in vitro cell exposure systems in hyperoxia and hypoxia

Exposure of cultured cells to changing gaseous environments is used as a model for understanding both the immediate and long-term effects of such exposures on lung cells in vivo. We conducted experiments with polystyrene tissue culture flasks and plates to determine the time course of changes in oxygen concentration occurring under in vitro conditions. Only a few minutes were required for the concentration of oxygen in the environmental chamber to reach equilibrium with that of the flushing gas. However, >3 h were required for the oxygen content in the medium in the tissue culture flasks and plates to achieve equilibrium. The low solubility of oxygen in aqueous solutions and the limited diffusion of oxygen through a boundary layer of gas above the medium are the major barriers to rapid oxygen transport into the culture medium. The delay in achieving the desired PO(2) within the culture medium limits the temporal precision of any assessment of the correlation of cellular events with the concentration of oxygen to which those cells are exposed.     

Changes in eggshell permeability to oxygen during the early developmental stages in diapause eggs of Bombyx mori

An apparatus for direct measurement of the eggshell permeability to oxygen was devised to test the hypothesis that diapause initiation in the Bombyx mori egg is caused by the eggshell becoming insufficiently perrneable to air to allow further embryogenesis. Using this apparatus, it was found that permeability of the eggshell to oxygen decreased dramatically during the first 2 days of incubation in prospective diapause eggs, but no appreciable changes were found in nondiapause eggs for the first 6 days of incubation. The rates of oxygen uptake by diapause and nondiapause eggs increased in a similar pattern for 26 h after oviposition. Thereafter, the rate of oxygen uptake in the former decreased while that of latter continuously increased. The cause and physiological meaning of the rapid drop of eggshell permeability just before diapause initiation are obscure. It is suggested that the decrease in oxygen uptake may be due to decreased eggshell permeability to oxygen.     

Generation of oxygen deficiency in cell culture using a two-enzyme system to evaluate agents targeting hypoxic tumor cells

The poor and aberrant vascularization of solid tumors makes them susceptible to localized areas of oxygen deficiency that can be considered sites of tumor vulnerability to prodrugs that are preferentially activated to cytotoxic species under conditions of low oxygenation. To readily facilitate the selection of agents targeted to oxygen-deficient cells in solid tumors, we have developed a simple and convenient two-enzyme system to generate oxygen deficiency in cell cultures. Glucose oxidase is employed to deplete oxygen from the medium by selectively oxidizing glucose and reducing molecular oxygen to hydrogen peroxide; an excess of catalase is also used to scavenge the peroxide molecules. Rapid and sustained depletion of oxygen occurs in medium or buffer, even in the presence of oxygen at the liquid/air interface. Studies using CHO/AA8 Chinese hamster cells, EMT6 murine mammary carcinoma cells, and U251 human glioma cells indicate that this system generates an oxygen deficiency that produces activation of the hypoxia-targeted prodrug KS119. This method of generating oxygen deficiency in cell culture is inexpensive, does not require cumbersome equipment, permits longer incubation times to be used without the loss of sample volume, and should be adaptable for high-throughput screening in 96-well plates.