THE BIOCHEMISTRY OF THE NITRIFYING ORGANISMS: PART 8. THE EFFECTS OF OXYGEN TENSION, NITRITE CONCENTRATION, AND CYANATE CONCENTRATION ON NITRITE OXIDATION BY NITROBACTER

1964 ◽  
Vol 42 (8) ◽  
pp. 1217-1224 ◽  
Author(s):  
W. D. Butt ◽  
H. Lees
Keyword(s):  
Oxygen Tension ◽  
Nitrite Oxidation ◽  
Nitrite Concentration ◽  
Whole Cells ◽  
Oxygen Tensions

The effects of various nitrite concentrations and oxygen tensions on nitrite oxidation by whole cells of Nitrobacter and by cell-free extracts have been investigated. The results, taken together with the effect of cyanate on the oxidation, suggest that cyanate inhibits nitrite oxidation in whole cells by impeding transfer of nitrite from the medium to the site of nitrite oxidation.

Gas Tensions in the Lungs and Major Blood Vessels of the Urodele Amphibian, Amphiuma Tridactylum

1971 ◽  
Vol 55 (1) ◽  
pp. 47-61
Author(s):  
DANIEL P. TOEWS ◽  
G. SHELTON ◽  
D. J. RANDALL
Keyword(s):  
Carbon Dioxide ◽  
Pulmonary Artery ◽  
Inferior Vena Cava ◽  
Blood Vessels ◽  
Pulmonary Vein ◽  
Oxygen Tension ◽  
Inferior Vena ◽  
Vena Cava ◽  
Dorsal Aorta ◽  
Oxygen Tensions

1. Oxygen and carbon dioxide tensions were determined in the lungs and in blood from the dorsal aorta, pulmonary vein, pulmonary artery and inferior vena cava in the intact, free swimming, Amphiuma. At 15° C this animal was submerged for a large part of the time and surfaced briefly to breathe at variable time intervals, the mean period being 45 min. 2. Oxygen tensions in the lungs and in all blood vessels oscillated with the breathing cycles, falling gradually during the period of submersion and rising rapidly after the animal breathed. The absolute level of oxygen tension did not appear to constitute the effective signal beginning or ending a series of breathing movements. 3. A small oxygen gradient existed between lungs and blood in the pulmonary vein immediately after a breath. The gradient increased in size as an animal remained submerged due, it is suggested, to lung vasoconstriction increasing the transfer factor. 4. Blood in the dorsal aorta had a lower oxygen tension than that in the pulmonary vein. A right-to-left shunt occurred as blood moved through the heart. The degree of shunting increased as the animal remained submerged and pulmonary vasoconstriction occurred. Left-to-right shunt was relatively insignificant since oxygen tensions in the inferior vena cava and pulmonary artery were very similar. 5. Carbon dioxide tensions were relatively constant during the breathing-diving cycle since Amphiuma removed almost all of this gas through the skin.

scholarly journals Oxygen-sensitive stages of the cell cycle of human diploid cells.

1978 ◽  
Vol 78 (2) ◽  
pp. 390-400 ◽  
Author(s):  
A K Balin ◽  
D B Goodman ◽  
H Rasmussen ◽  
V J Cristofalo
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Oxygen Tension ◽  
Cycle Growth ◽  
Partial Pressures ◽  
Oxygen Sensitive ◽  
Oxygen Tensions ◽  
Human Diploid Cells ◽  
Diploid Cells

We had established that growth of human diploid WI-38 cells is reversibly inhibited by elevated partial pressures of oxygen (PO2) and we were interested in determining where in the cell cycle growth was delayed. A technique combining cytospectrophotometry and autoradiography was used to determine cell cycle parameters. Confluent cells that were subcultivated and exposed to a PO2 of 365 +/- 8 mm Hg were delayed primarily after DNA synthesis but before metaphase. At a PO2 of 590 +/- 35 mm Hg, most cells did not initiate DNA synthesis, and the few that did, failed to complete the process. When exponentially growing cells that had already begun DNA synthesis were exposed to a PO2 of 590 p 35 mm Hg, they accumulated after completing DNA synthesis but before initiating mitosis. The rate at which (3H)thymidine was incorporated into DNA was inversely correlated with oxygen tension (PO2 of 135--590 mm Hg). These results suggest that the process most sensitive to oxygen causes cells to be delayed after DNA synthesis but before metaphase. Slightly higher PO2's were needed to inhibit the initiation of DNA synthesis. Further, the rate of DNA synthesis is decreased by elevated oxygen tensions.

The Relationship Between Hydrogen Evolution, Hydrogen Exchange, Nitrogen Fixation, and Applied Oxygen Tension in Soybean Root Nodules

1963 ◽  
Vol 16 (3) ◽  
pp. 669 ◽  
Author(s):  
FJ Bergersen
Keyword(s):  
Nitrogen Fixation ◽  
Hydrogen Evolution ◽  
Oxygen Tension ◽  
Hydrogen Exchange ◽  
Root Nodules ◽  
Soybean Root ◽  
Oxygen Tensions ◽  
The Relationship

Hydrogen evolution and exchange a~d nitrogen fixation by detached soybean root nodules were studied at various external oxygen tensions (p02). The main findings were:

Transcutaneous Oxygen Tension in the Dysvascular Foot with Infection

Foot & Ankle ◽  
1993 ◽  
Vol 14 (5) ◽  
pp. 254-256 ◽  
Author(s):  
Michael S. Pinzur ◽  
Rodney Stuck ◽  
Ronald Sage ◽  
Helen Osterman
Keyword(s):  
Wound Healing ◽  
Vascular Disease ◽  
Oxygen Tension ◽  
Foot And Ankle ◽  
Peripheral Vascular ◽  
Transcutaneous Oxygen Tension ◽  
Transcutaneous Oxygen ◽  
Systemic Sepsis ◽  
Appreciable Increase ◽  
Oxygen Tensions

Eight adult insulin-requiring diabetics with peripheral vascular disease were admitted with foot infection and signs of systemic sepsis. Transcutaneous oxygen tension was measured at the foot and ankle prior to surgery. None of the values were sufficient to support wound healing. Four of the patients underwent open ray resection and four open midfoot amputation. After resolution of the local infections, transcutaneous oxygen tensions were repeated. Seven of the eight patients exhibited an appreciable increase in the value following decompression of the foot infection, sufficient to support wound healing.

scholarly journals Effect of pH and nitrite concentration on nitrite oxidation rate

2011 ◽  
Vol 102 (19) ◽  
pp. 8741-8747 ◽  
Author(s):  
E. Jiménez ◽  
J.B. Giménez ◽  
M.V. Ruano ◽  
J. Ferrer ◽  
J. Serralta
Keyword(s):  
Oxidation Rate ◽  
Nitrite Oxidation ◽  
Nitrite Concentration ◽  
Effect Of Ph

POLYHYDRIC ALCOHOL PRODUCTION BY OSMOPHILIC YEASTS: EFFECT OF OXYGEN TENSION AND INORGANIC PHOSPHATE CONCENTRATION

1957 ◽  
Vol 3 (4) ◽  
pp. 559-567 ◽  
Author(s):  
J. F. T. Spencer ◽  
Ping Shu
Keyword(s):  
Oxygen Tension ◽  
Inorganic Phosphate ◽  
Opposite Effect ◽  
Ethanol Yield ◽  
Phosphate Concentration ◽  
Alcohol Production ◽  
Lower Oxygen ◽  
Oxygen Tensions ◽  
Effect Of Oxygen ◽  
Very High

A study was made of the effects of oxygen tension and inorganic phosphate concentration on the production of glycerol, arabitol, and ethanol by a strain of osmophilic yeast. Increasing the oxygen tension increased the yields of glycerol and arabitol and decreased the yield of ethanol, while increasing the concentration of inorganic phosphate had the opposite effect.The changes in yields of products with increasing phosphate concentration were most pronounced at a partial pressure of oxygen of 280 mm. of mercury. At lower oxygen tensions the yields of polyols were low and the yield of ethanol was high at all concentrations of phosphate, while at very high oxygen tensions the opposite effect was observed. When the ethanol yield was high, the respiratory quotient was also high. These results are discussed in relation to the oxidative phosphate-lack theory of the Pasteur effect.

Dependence of mitosis and respiration in roots upon oxygen tension

1961 ◽  
Vol 154 (954) ◽  
pp. 109-129 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Uptake ◽  
Oxygen Tension ◽  
Oxygen Requirement ◽  
Anaerobic Conditions ◽  
Root Tips ◽  
Carbon Dioxide Output ◽  
Lower Oxygen ◽  
Oxygen Tensions ◽  
The Relationship

Excised pea-root tips were incubated for 4 h in gas mixtures containing 0.00001 to 100% oxygen, in order to determine the effect upon mitosis. Below 0.0005% oxygen, mitosis was completely arrested. Between 0.001 and 0.02% oxygen, cells initially in mitosis completed division, but no more cells started dividing. Between 0.05 and 0.2% oxygen, cells initially in interphase entered division, but did not finish. Above 0.5% oxygen, all cells not prevented from dividing by excision finished division within 4 h. After exposure to 0.05% oxygen for 4 h, an excessive proportion of cells was found in prophase; in 0.1% oxygen an excess of metaphases, and in 0.2% oxygen an excess of telophases resulted. The oxygen uptake and carbon dioxide output of root tips were measured in a range of oxygen tensions and in anaerobic conditions. The relationship between oxygen uptake and oxygen tension was hyperbolic; a half maximum rate of oxygen uptake was obtained at about 10% oxygen. It was concluded that the respiration of root tips was limited by slow diffusion of oxygen through the tissue. From the carbon dioxide output it was estimated that the amount of energy available to isolated root tips under anaerobic conditions was about 1% of that available under aerobic conditions. Possible mechanisms whereby extreme oxygen-lack could arrest mitosis were considered. It was shown that the arrest was not due to abolition of a gross supply of energy. No evidence was obtained as to what other mechanism might be operative. An hypothesis was formulated in an attempt to explain the complicated relationship between mitosis and oxygen tension. It was assumed that the visible phases of mitosis are immediately preceded by a phase with a higher requirement for oxygen than mitosis, and that preceding this is an earlier phase with a lower oxygen requirement than mitosis.

Critical oxygen tensions in newborn, young, and adult mice

1963 ◽  
Vol 205 (2) ◽  
pp. 325-330 ◽  
Author(s):  
S. Cassin
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Tension ◽  
Environmental Temperature ◽  
Mild Hypothermia ◽  
Newborn Mouse ◽  
Newborn Mice ◽  
Adult Mice ◽  
Critical Oxygen ◽  
Rate Of Oxygen Consumption ◽  
Oxygen Tensions

Critical oxygen tensions of newborn, young, and adult mice are presented. At neutral environmental temperature, oxygen consumption of newborn mice is unaffected by reducing the oxygen tension of inspired air to 85 mm Hg. Five-day-old mice, at neutral environmental temperature, tolerate a decrease in ambient oxygen tension to 100 mm Hg without a depression of oxygen consumption. Adult mice behave in a qualitatively similar fashion. When the ambient temperature is lowered below neutral, the mice are unable to maintain a constant oxygen consumption if hypoxia is induced. It appears as though the depression of oxygen consumption during hypoxia is linearly related to the hypothermic increment to metabolism: the greater the extra oxygen consumption, the more readily it is reduced. Although the newborn mouse is unable to combat hypothermia effectively, it does respond to mild hypothermia for short periods by increasing its rate of oxygen consumption. Evidence is presented of a rapid maturation of temperature controlling mechanisms during growth.

The Respiratory Physiology of the Marine Nematodes Enoplus Brevis (Bastian) and E. Communis (Bastian)

1973 ◽  
Vol 59 (1) ◽  
pp. 255-266
Author(s):  
H. J. ATKINSON
Keyword(s):  
Oxygen Consumption ◽  
Body Size ◽  
Oxygen Tension ◽  
Dry Weight ◽  
Respiratory Physiology ◽  
Rate Of Oxygen Consumption ◽  
Oxygen Tensions ◽  
The Difference ◽  
Relationship Of ◽  
The Relationship

1. The rate of oxygen consumption of individual males of Enoplus brevis and E. communis was measured at 15 °C and at each of four oxygen tensions, 135, 75, 35, and 12 Torr, after at least 12 h experience of these conditions. 2. It was clearly demonstrated that the level of oxygen consumption of both species was reduced by each lowering of the imposed oxygen tension. 3. In all cases the oxygen consumption of each species fell with increasing body size. On a unit dry-weight basis the oxygen consumption of E. brevis is greater than that of the larger E. communis, but after allowing for the difference of body size the two species have more or less similar oxygen uptakes at all oxygen tensions. 4. In E. brevis oxygen tension influenced the relationship of body size and metabolism, the slope relating oxygen consumption and body weight becomes steeper with decreasing oxygen tension. This effect was not shown by E. communis. 5. Some general factors influencing the availability of oxygen to nematodes are considered.

scholarly journals The Influence of Hypoxemia and Cobalt on Erythropoietin Production in the Isolated Perfused Dog Kidney

Blood ◽  
1967 ◽  
Vol 29 (1) ◽  
pp. 114-125 ◽  
Author(s):  
JAMES W. FISHER ◽  
J. W. LANGSTON
Keyword(s):  
Oxygen Tension ◽  
Renal Cells ◽  
Isolated Perfused Kidney ◽  
Blood Flows ◽  
Cellular Changes ◽  
Erythropoietin Production ◽  
Bubble Oxygenator ◽  
Dog Kidney ◽  
Oxygen Tensions ◽  
Perfused Kidney

Abstract Isolated dog kidneys were perfused with blood at normal and reduced oxygen tensions with and without cobalt. Erythropoietin titers were found to be significantly increased in the blood perfusates from kidneys perfused with blood at lowered oxygen tensions, while no change in erythropoietin was seen when kidneys were perfused with blood at a normal oxygen tension. Cobalt produced significant increases in erythropoietin levels in the perfusates with normal as well as reduced oxygen tension blood, but its effect was more marked when the kidneys were perfused with hypoxic blood. Renal blood flows were higher when the dogs’ own lungs were used to oxygenate the blood than when a bubble oxygenator was used in the system. However, hypoxic blood resulted in significant increases in erythropoietin production in both systems. In studies of the kidney histology from both perfusion systems with hypoxic and normal oxygen tension blood, most of the kidneys demonstrated varying degrees of glomerular congestion. No correlation was found between erythropoietin elaboration and renal congestion or other degenerative cellular changes in the kidney. Therefore, it does not seem likely that erythropoietin produced in the isolated perfused kidney is due to histologic damage to renal cells. These findings support the concept that increased erythropoietin production in the isolated perfused kidney in response to cobalt or hypoxic blood is a direct effect of these stimuli on the kidney.

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