Artykuły w czasopismach: „Oxygen uptake rates”

1

Mines, Richard O. "Oxygen transfer parameters and oxygen uptake rates revisited". Journal of Environmental Science and Health, Part A 55, nr 4 (28.11.2019): 345–53. http://dx.doi.org/10.1080/10934529.2019.1694817.

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Rotem, Avi, Menmet Toner, Ronald G. Tompkins i Martin L. Yarmush. "Oxygen uptake rates in cultured rat hepatocytes". Biotechnology and Bioengineering 40, nr 10 (5.12.1992): 1286–91. http://dx.doi.org/10.1002/bit.260401020.

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Kizaki, Z., i R. G. Thurman. "Stimulation of oxygen uptake by glucagon is oxygen dependent in perfused rat liver". American Journal of Physiology-Gastrointestinal and Liver Physiology 256, nr 2 (1.02.1989): G369—G376. http://dx.doi.org/10.1152/ajpgi.1989.256.2.g369.

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Livers from well-fed female Sprague-Dawley rats (100-150 g) were perfused at flow rates of 4 or 8 ml.g liver-1.min-1 to deliver O2 to the organ at various rates. During perfusion at normal flow rates (4 ml.g-1.min-1), glucagon (10 nM) increased O2 uptake in perfused liver by approximately 40 mumol.g-1.h-1. In contrast, glucagon increased O2 uptake by nearly 100 mumol.g-1.h-1 when livers were perfused at high flow rates. Increase in O2 uptake was directly proportional to flow rate and was blocked partially by infusion of phorbol myristate acetate (100 nM) before glucagon. Increase in O2 uptake due to elevated flow was not due to enhanced glucagon delivery, since infusion of 120 nM glucagon at normal flow rates only increased O2 uptake by approximately 40 mumol.g-1.h-1. On the other hand, when O2 tension in the perfusate was manipulated at normal flow rates, the stimulation of O2 uptake by glucagon increased proportional to the average O2 tension in the liver. Infusion of 8-bromo-adenosine 3',5'-cyclic monophosphate (BrcAMP; 25 microM) also increased O2 uptake more than twice as much at high compared with normal flow rates. In the presence of angiotensin II (5 nM), a hormone that increases intracellular calcium, glucagon increased O2 uptake by nearly 100 mumol.g-1.h-1 at normal flow rates. Infusion of glucagon or BrcAMP into livers perfused at normal flow rates increased state 3 rates of O2 uptake of subsequently isolated mitochondria significantly by approximately 25%. In contrast, perfusion with glucagon or BrcAMP at high flow rates increased mitochondrial respiration by 50-60%. Glucagon addition acutely to suspensions of mitochondria, however, had no effect on O2 uptake. These data are consistent with reports that glucagon administration in vivo or treatment of intact cells with glucagon increases O2 uptake of subsequently isolated mitochondria, a phenomenon that can account for the observed increase in O2 uptake in livers perfused at high flow rates with glucagon. Furthermore, these results are consistent with the hypothesis that the effect of glucagon on mitochondria is O2 dependent in the perfused liver. This is most likely due to an effect of intracellular calcium on a mechanism mediated via cAMP.(ABSTRACT TRUNCATED AT 250 WORDS)

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Qu, Wei, Zhi Zhong, Gavin E. Arteel i Ronald G. Thurman. "Stimulation of oxygen uptake by prostaglandin E2 is oxygen dependent in perfused rat liver". American Journal of Physiology-Gastrointestinal and Liver Physiology 275, nr 3 (1.09.1998): G542—G549. http://dx.doi.org/10.1152/ajpgi.1998.275.3.g542.

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The aim of this study was to determine if the effect of prostaglandin E2(PGE2) on hepatic oxygen uptake was affected by oxygen tension. Livers from fed female Sprague-Dawley rats were perfused at normal or high flow rates (4 or 8 ml ⋅ g−1 ⋅ min−1) to vary local oxygen tension within the liver lobule. During perfusion at normal flow rates, PGE2 (5 μM) infusion increased oxygen uptake by about 50 μmol ⋅ g−1 ⋅ h−1; however, when livers were perfused at high flow rates, the increase was nearly twice as large. Simultaneously, glucose output was increased rapidly by about 50%, whereas glycolysis was decreased about 60%. When flow rate was held constant, increases in oxygen uptake due to PGE2 were proportional to oxygen delivery. Infusion of PGE2 into livers perfused at normal flow rates increased state 3 rates of oxygen uptake of subsequently isolated mitochondria by about 25%; however, rates were increased 50–75% in mitochondria isolated from livers perfused at high flow rates. Thus it is concluded that PGE2stimulates oxygen uptake via mechanisms regulated by oxygen tension in perfused rat liver. High flow rates also increased basal rates of oxygen uptake: this increase was prevented by inactivation of Kupffer cells with GdCl3. In addition, conditioned medium from Kupffer cells incubated at high oxygen tension (75% oxygen) stimulated oxygen uptake of isolated parenchymal cells by >30% and elevated PGE2production about twofold compared with Kupffer cells exposed to normal air-saturated buffer (21% oxygen). These effects were blocked completely by both indomethacin and nisoldipine. These data support the hypothesis that oxygen stimulates Kupffer cells to release mediators such as PGE2 which elevate oxygen consumption in parenchymal cells, possibly by mechanisms involving cyclooxygenase and calcium channels.

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Carlson, John S., i Geraldine A. Naughton. "An Examination of the Anaerobic Capacity of Children Using Maximal Accumulated Oxygen Deficit". Pediatric Exercise Science 5, nr 1 (luty 1993): 60–71. http://dx.doi.org/10.1123/pes.5.1.60.

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The purpose of this study was to determine the anaerobic capacity of children using the maximal accumulated oxygen deficit technique (AOD). Eighteen healthy children (9 boys, 9 girls) with a mean age of 10.6 years volunteered as subjects. Peak oxygen uptake and submaximal steady-state oxygen uptake tests were conducted against progressive constant work rates on a Cybex cycle ergometer. Supramaximal work rates were predicted from the linear regression of submaximal steady-state work rates and oxygen uptakes to equal 110, 130, and 150% of peak oxygen uptake. Results indicated a significant interaction in the responses of both sexes when the accumulated oxygen deficit data were expressed in both absolute and relative terms. The profile of accumulated oxygen deficits across the three intensities indicated a downward shift in the girls responses between the 110 and 150% supramaximal tests. This trend was not evident in the boys’ responses. Intraclass correlations conducted on test-retest data indicated that compared to the boys, the reliability of the girls in the accumulated oxygen deficits in liters and ml·kg−1 was poorer.

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Nakagawa, Y., T. Matsumura, M. Goto, W. Qu, F. C. Kauffman i R. G. Thurman. "Increase in oxygen uptake due to arachidonic acid is oxygen dependent in the perfused liver". American Journal of Physiology-Gastrointestinal and Liver Physiology 266, nr 5 (1.05.1994): G953—G959. http://dx.doi.org/10.1152/ajpgi.1994.266.5.g953.

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The purpose of this study was to determine whether the effect of arachidonic acid on hepatic O2 uptake is O2 dependent and which region of the liver lobule it affects. In livers perfused at normal flow rates, infusion of arachidonate increased O2 uptake significantly by about 20-25 mumol.g-1.h-1. When the flow rate was doubled to make the hepatic O2 gradient shallower, the increase in O2 uptake due to arachidonate was two to three times larger (i.e., approximately 50 mumol.g-1.h-1). In livers perfused in the retrograde direction, maximal rates of O2 uptake were about twofold higher in upstream pericentral than in downstream periportal regions, and arachidonic acid nearly doubled O2 uptake in downstream areas without affecting rates in upstream regions. Thus it is concluded that arachidonate stimulates O2 uptake in an O2-dependent manner. This effect was sensitive to an inhibitor of the lipoxygenase, nordihydroguaiaretic acid, in perfused liver but not in isolated hepatocytes. In addition, conditioned medium from Kupffer cells incubated at high O2 tension stimulated parenchymal cell O2 uptake. Furthermore, arachidonate increased intracellular Ca2+ in isolated Kupffer cells in a dose-dependent manner. These findings suggest that eicosanoids produced by nonparenchymal cells participate in a hepatic O2 sensor mechanism involving Ca2+ that regulates O2 uptake by parenchymal cells in the liver.

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Garcı́a-Ochoa, F., E. Gómez Castro i V. E. Santos. "Oxygen transfer and uptake rates during xanthan gum production". Enzyme and Microbial Technology 27, nr 9 (listopad 2000): 680–90. http://dx.doi.org/10.1016/s0141-0229(00)00272-6.

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Huang, Jerry Y. C., Meng-Dawn Cheng i James T. Mueller. "Oxygen uptake rates for determining microbial activity and application". Water Research 19, nr 3 (1985): 373–81. http://dx.doi.org/10.1016/0043-1354(85)90098-3.

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Peddie, F. L., W. J. Simpson, B. V. Kara, Sarah C. Robertson i J. R. M. Hammond. "MEASUREMENT OF ENDOGENOUS OXYGEN UPTAKE RATES OF BREWERS' YEASTS". Journal of the Institute of Brewing 97, nr 1 (2.01.1991): 21–25. http://dx.doi.org/10.1002/j.2050-0416.1991.tb01048.x.

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Milley, J. R. "Uptake of exogenous substrates during hypoxia in fetal lambs". American Journal of Physiology-Endocrinology and Metabolism 254, nr 5 (1.05.1988): E572—E578. http://dx.doi.org/10.1152/ajpendo.1988.254.5.e572.

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Fetal uptakes of oxygen, glucose, lactate, and alpha-amino-nitrogen containing substrates were measured in eight near-term fetal lambs by simultaneously drawing blood samples from the umbilical vein and descending aorta, then measuring umbilical blood flow using the microsphere method. These procedures were repeated after 3 h of hypoxia induced by lowering maternal inspired oxygen concentration. On the next day the experiment was repeated, except the ewes were first made hypoxic then allowed to breathe room air. These conditions decreased the delivery of oxygen, but not the delivery of other metabolic substrates to the fetus. During hypoxia, fetal oxygen uptake was 82% of normal (mean of both days); fetal glucose and amino-nitrogen uptakes were 74 and 23% of normal, respectively, and fetal lactate uptake became insignificant. These data indicate that endogenous rather than exogenous substrates are used to support fetal oxidative metabolism during hypoxia. Also, because exogenous uptake of amino-nitrogen is less than normal nitrogen accretion rates, fetal growth must be reduced as a consequence of 3-4 h of hypoxia.

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Nilsson, Göran E., Sara Östlund-Nilsson, Rose Penfold i Alexandra S. Grutter. "From record performance to hypoxia tolerance: respiratory transition in damselfish larvae settling on a coral reef". Proceedings of the Royal Society B: Biological Sciences 274, nr 1606 (26.09.2006): 79–85. http://dx.doi.org/10.1098/rspb.2006.3706.

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The fastest swimming fishes in relation to size are found among coral reef fish larvae on their way to settle on reefs. By testing two damselfishes, Chromis atripectoralis and Pomacentrus amboinensis , we show that the high swimming speeds of the pre-settlement larvae are accompanied by the highest rates of oxygen uptake ever recorded in ectothermic vertebrates. As expected, these high rates of oxygen uptake occur at the cost of poor hypoxia tolerance. However, hypoxia tolerance is needed when coral reef fishes seek nocturnal shelter from predators within coral colonies, which can become severely hypoxic microhabitats at night. When the larvae settle on the reef, we found that they go through a striking respiratory transformation, i.e. the capacity for rapid oxygen uptake falls, while the ability for high-affinity oxygen uptake at low oxygen levels is increased. This transition to hypoxia tolerance is needed when they settle on the reef; this was strengthened by our finding that small resident larvae of Acanthochromis polyacanthus , a damselfish lacking a planktonic larval stage, do not display such a transition, being well adapted to hypoxia and showing relatively low maximum rates of oxygen uptake that change little with age.

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Felder, Michael L., Aaron D. Simmons, Robert L. Shambaugh i Vassilios I. Sikavitsas. "Effects of Flow Rate on Mesenchymal Stem Cell Oxygen Consumption Rates in 3D Bone-Tissue-Engineered Constructs Cultured in Perfusion Bioreactor Systems". Fluids 5, nr 1 (8.03.2020): 30. http://dx.doi.org/10.3390/fluids5010030.

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Bone grafts represent a multibillion-dollar industry, with over a million grafts occurring each year. Common graft types are associated with issues such as donor site morbidity in autologous grafts and immunological response in allogenic grafts. Bone-tissue-engineered constructs are a logical approach to combat the issues commonly encountered with these bone grafting techniques. When creating bone-tissue-engineered constructs, monitoring systems are required to determine construct characteristics, such as cellularity and cell type. This study aims to expand on the current predictive metrics for these characteristics, specifically analyzing the effects of media flow rate on oxygen uptake rates (OURs) of mesenchymal stem cells seeded on poly(L-lactic acid) (PLLA) scaffolds cultured in a flow perfusion bioreactor. To do this, oxygen consumption rates were measured for cell/scaffold constructs at varying flow rates ranging from 150 to 750 microliters per minute. Residence time analyses were performed for this bioreactor at these flow rates. Average observed oxygen uptake rates of stem cells in perfusion bioreactors were shown to increase with increased oxygen availability at higher flow rates. The residence time analysis helped identify potential pitfalls in current bioreactor designs, such as the presence of channeling. Furthermore, this analysis shows that oxygen uptake rates have a strong linear correlation with residence times of media in the bioreactor setup, where cells were seen to exhibit a maximum oxygen uptake rate of 3 picomoles O2/hr/cell.

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Naylor, J. K., E. W. Taylor i D. B. Bennett. "Oxygen uptake of developing eggs of Cancer pagurus (Crustacea: Decapoda: Cancridae) and consequent behaviour of the ovigerous females". Journal of the Marine Biological Association of the United Kingdom 79, nr 2 (kwiecień 1999): 305–15. http://dx.doi.org/10.1017/s0025315498000332.

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This study investigated factors affecting the metabolic rate of Cancer pagurus eggs. The oxygen uptake of portions of the egg mass and recently hatched zoeae was measured. Oxygen uptake of the eggs of an individual animal was found to vary widely, with measured mean values under normoxic conditions ranging from 38 to 250 μmoles O2 kg−1 min−1. Mean values for the oxygen uptake of zoeae ranged from 958 to 1168 μmoles O2 kg−1 min−1. Mean rates of oxygen uptake of the eggs generally increased with increasing seasonal temperature and advancing developmental stage. Rates of oxygen uptake were maintained over a wide range of ambient oxygen partial pressures. As oxygen partial pressure in the seawater surrounding the eggs fell from a critical value (Pc) of between 60 and 90 mm Hg, the oxygen uptake of the eggs also declined. Mean values for ambient oxygen partial pressures within the egg mass in vivo ranged from 34 to 98 mm Hg. Adult female C. pagurus appear to be able to detect conditions within the egg mass and adjust their egg ventilation behaviour accordingly. Active egg mass ventilation by the adult increased as the eggs became more developed and their oxygen demands increased.

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Chinet, A. E., i J. Mejsnar. "Is resting muscle oxygen uptake controlled by oxygen availability to cells?" Journal of Applied Physiology 66, nr 1 (1.01.1989): 253–60. http://dx.doi.org/10.1152/jappl.1989.66.1.253.

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To estimate oxidative capacity of noncontracting rat skeletal muscle, the isolated gracilis muscle was perfused at various high flow rates with high-PO2 (88 kPa) saline-albumin solution and simultaneously perifused at either low (6.3 kPa) or high PO2 in a calorimeter at 28 degrees C. Under low-PO2 perifusion, specific O2 consumption and heat production rates (MO2 and E, respectively) were flow-rate dependent. E values were all larger than those obtained on blood-perfused preparations at 28 degrees C. MO2 reached 0.47 mumol.min-1.g muscle-1 and E reached 4 mW/g. Normalized to 36 degrees C by means of activation energies determined from 30 and 36 degrees C measurements on nonperfused gracilis strips, these maxima correspond to three times the largest MO2 measured by other authors in blood-autoperfused gracilis. Increasing perifusion PO2 from 6.3 to 88 kPa sharply decreased MO2. These results confirm that MO2 of blood-perfused skeletal muscles in vitro (and a fortiori in vivo) is kept much below its maximum for a noncontracting organ; they also suggest that this maximum MO2 is not necessarily an effect of unphysiologically high PO2 in the tissue cells.

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Boyle, W. C., B. G. Hellstrom i L. Ewing. "Oxygen Transfer Efficiency Measurements Using Off-Gas Techniques". Water Science and Technology 21, nr 10-11 (1.10.1989): 1295–300. http://dx.doi.org/10.2166/wst.1989.0327.

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The off-gas technique for measuring oxygen transfer efficiency in aeration tanks under process conditions was proposed as an accurate technique for calibrating or verifying on-line methods used to estimate oxygen uptake rates. The theoretical development of the off-gas technique was presented. Application of this technique in verifying or calibrating existing on-line methods for estimating oxygen uptake rate was presented. Direct application as an on-line method for estimating oxygen uptake rate was also discussed.

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Walsh, William A., i William A. Lund Jr. "Oxygen consumption by eggs of the grubby, Myoxocephalus aenaeus, and the longhorn sculpin, Myoxocephalus octodecemspinosus". Canadian Journal of Zoology 67, nr 7 (1.07.1989): 1613–19. http://dx.doi.org/10.1139/z89-230.

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Oxygen consumption rates of individual eggs of the grubby, Myoxocephalus aenaeus, and the longhorn sculpin, Myoxocephalus octodecemspinosus, were determined by microrespirometry. Eggs of both species were incubated in temperature – salinity combinations (grubby: in 2, 5, 8 °C at 10, 12.5, 15, 20, 25, 30, 35 parts per thousand (ppt); longhorn sculpin: in 2, 5, 8 °C at 15, 17.5, 20, 25, 30, 35 ppt) to determine the effects of these abiotic factors and development on oxygen consumption rates. Respiration rates of eggs of both species were not affected significantly by constant salinities. Multiple regression analyses demonstrated that the natural logarithms of oxygen uptake rates increased linearly with the temperature – age (in hours after fertilization) interaction and parabolically with age in both species. Oxygen consumption rates increased at hatching. Acute salinity changes did not affect embryonic oxygen consumption by either species. An acute temperature increase, however, elicited increased oxygen uptake by longhorn sculpin embryos (Q10 = 2.56).

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Makino, Yoshio, Masayuki Ichimura, Yoshinori Kawagoe i Seiichi Oshita. "Cytochrome c Oxidase as a Cause of Variation in Oxygen Uptake Rates Among Vegetables". Journal of the American Society for Horticultural Science 132, nr 2 (marzec 2007): 239–45. http://dx.doi.org/10.21273/jashs.132.2.239.

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The effect of cytochrome c oxidase, the terminal oxidase in the respiratory chain, on O2 uptake by vegetables was investigated. Broccoli florets (Brassica oleracea L. var. italica Plenck), spinach leaves (Spinacia oleracea L.), and onion bulbs (Allium cepa L.), which were expected to show rapid, moderate, and slow O2 uptake rates, respectively, were used in the current study. The order of O2 uptake rate measured by a closed method with a gas chromatograph was broccoli florets > spinach leaves > onion bulbs. Cytochrome c oxidase activity of mitochondrial preparations from onion bulbs was lower than that of the other vegetables, as was the O2 uptake rate. The higher O2 uptake rate of broccoli florets compared to spinach leaves was caused by higher cytochrome c oxidase activity of the floral buds. Grayscale luminance was used to determine the extent and distribution of staining in the tissues due to cytochrome c oxidase activity. Active O2 uptake by floral buds of broccoli florets was caused by the high concentration of cytochrome c oxidase in the pistil and petal. The absorbance of stems of broccoli florets at 823 nm, possibly derived from absorption by copper in cytochrome c oxidase, was higher than that of onion scale leaves, which agreed with the results of cytochrome c oxidase staining. We concluded that cytochrome c oxidase contributed to the O2 uptake rate by vegetables and that cytochrome c oxidase was one of the important causes for variation in O2 uptake rates among vegetables.

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Fowden, A. L., i M. Silver. "Glucose and oxygen metabolism in the fetal foal during late gestation". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 269, nr 6 (1.12.1995): R1455—R1461. http://dx.doi.org/10.1152/ajpregu.1995.269.6.r1455.

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With the use of [U-14C]glucose tracer methodology, the rates of umbilical uptake, utilization, oxidation, and production of glucose were determined in nine chronically catheterized fetal foals in the fed state between 268 and 325 days of gestation (term approximately 335 days). At the same time, the rates of umbilical O2 and lactate uptake were measured in all nine fetuses by Fick principle. The mean fetal rates of umbilical glucose uptake, glucose utilization, and CO2 production from glucose carbon were 36.9 +/- 2.5, 36.4 +/- 1.7, and 117.7 +/- 17.4 mumol.min-1.kg fetal body wt-1, respectively (n = 9). Endogenous glucose production was therefore negligible in the fetal foal in the fed state. Production of CO2 from glucose carbon accounted for 40.9 +/- 6.5% of the umbilical O2 uptake, which averaged 292 +/- 15 mumol.min-1.kg-1 (n = 9). No significant changes in fetal glucose or O2 metabolism were observed with increasing gestational age. The rates of umbilical glucose uptake, glucose utilization, and CO2 production from glucose carbon (P < 0.01), but not the rate of umbilical O2 uptake (P > 0.05), were positively correlated with the fetal blood glucose level. There was a significant umbilical lactate uptake in the fetuses older than 290 days (12.3 +/- 4.1 mumol.min-1.kg-1, n = 5, P < 0.05) but not in the younger animals (6.2 +/- 9.6 mumol.min-1.kg-1, n = 4, P > 0.05). Hence, glucose is used for both oxidative and nonoxidative metabolism in utero and is a major, although not the sole, oxidative substrate in the fetal foal during late gestation.

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Bouyoucos, Ian A., Colin A. Simpfendorfer i Jodie L. Rummer. "Estimating oxygen uptake rates to understand stress in sharks and rays". Reviews in Fish Biology and Fisheries 29, nr 2 (10.04.2019): 297–311. http://dx.doi.org/10.1007/s11160-019-09553-3.

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Wildish, David J., Laura Pavesi i Shawn M. C. Robinson. "Comparing oxygen uptake rates of driftwood and wrack generalist talitrid amphipods". Marine and Freshwater Behaviour and Physiology 51, nr 3 (4.05.2018): 203–11. http://dx.doi.org/10.1080/10236244.2018.1521701.

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Kwon, Eun Young, Curtis Deutsch, Shang-Ping Xie, Sunke Schmidtko i Yang-Ki Cho. "The North Pacific Oxygen Uptake Rates over the Past Half Century". Journal of Climate 29, nr 1 (22.12.2015): 61–76. http://dx.doi.org/10.1175/jcli-d-14-00157.1.

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Abstract The transport of dissolved oxygen (O2) from the surface ocean into the interior is a critical process sustaining aerobic life in mesopelagic ecosystems, but its rates and sensitivity to climate variations are poorly understood. Using a circulation model constrained to historical variability by assimilation of observations, the study shows that the North Pacific thermocline effectively takes up O2 primarily by expanding the area through which O2-rich mixed layer water is detrained into the thermocline. The outcrop area during the critical winter season varies in concert with the Pacific decadal oscillation (PDO). When the central North Pacific Ocean is in a cold phase, the winter outcrop window for the central mode water class (CMW; a neutral density range of γ = 25.6–26.6) expands southward, allowing more O2-rich surface water to enter the ocean’s interior. An increase in volume flux of water to the CMW density class is partly compensated by a reduced supply to the shallower densities of subtropical mode water (γ = 24.0–25.5). The thermocline has become better oxygenated since the 1980s partly because of strong O2 uptake. Positive O2 anomalies appear first near the outcrop and subsequently downstream in the subtropical gyre. In contrast to the O2 variations within the ventilated thermocline, observed O2 in intermediate water (density range of γ = 26.7–27.2) shows a declining trend over the past half century, a trend not explained by the open ocean water mass formation rate.

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Hofmann, A. F., E. T. Peltzer i P. G. Brewer. "Kinetic bottlenecks to respiratory exchange rates in the deep-sea – Part 1: Oxygen". Biogeosciences 10, nr 7 (25.07.2013): 5049–60. http://dx.doi.org/10.5194/bg-10-5049-2013.

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Abstract. Ocean warming is now reducing dissolved oxygen concentrations, which can pose challenges to marine life. Oxygen limits are traditionally reported simply as a static concentration threshold with no temperature, pressure or flow rate dependency. Here we treat the oceanic oxygen supply potential for heterotrophic consumption as a dynamic molecular exchange problem analogous to familiar gas exchange processes at the sea surface. A combination of the purely physico-chemical oceanic properties temperature, hydrostatic pressure, and oxygen concentration defines the ability of the ocean to provide the oxygen supply to the external surface of a respiratory membrane. This general oceanic oxygen supply potential is modulated by further properties such as the diffusive boundary layer thickness to define an upper limit to oxygen supply rates. While the true maximal oxygen uptake rate of any organism is limited by gas transport either across the respiratory interface of the organism itself or across the diffusive boundary layer around an organism, controlled by physico-chemical oceanic properties, it can never be larger than the latter. Here, we define and calculate quantities that describe this upper limit to oxygen uptake posed by physico-chemical properties around an organism and show examples of their oceanic profiles.

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Vendruscolo, Francielo, Márcio José Rossi, Willibaldo Schmidell i Jorge Luiz Ninow. "Determination of Oxygen Solubility in Liquid Media". ISRN Chemical Engineering 2012 (20.06.2012): 1–5. http://dx.doi.org/10.5402/2012/601458.

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The present work aimed at determining the oxygen saturation in culture medium used in the production of pigments by Monascus ruber CCT 3802. This estimation allows the correction and the minimization of errors on the specific oxygen uptake rates determination because the conversion of oxygen partial pressure to oxygen concentration requires accurate information on oxygen solubility in experimental incubation media. By adding hydrogen peroxide and then transforming into water and oxygen using catalase, it was possible to determinate the saturation concentration of 7.677 and 6.772 mgO2 L−1 in distilled water and in growth medium, respectively. The determination of these parameters makes possible the minimization of errors on the specific oxygen uptake rates determination, once many studies consider the saturation concentration in distilled water.

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Sousa, M. Céu, i J. Poiares-da-Silva. "A New Method for Assessing Metronidazole Susceptibility of Giardia lamblia Trophozoites". Antimicrobial Agents and Chemotherapy 43, nr 12 (1.12.1999): 2939–42. http://dx.doi.org/10.1128/aac.43.12.2939.

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ABSTRACT A quantitative, simple, and rapid assay has been developed to assess Giardia lamblia trophozoite sensitivity to metronidazole [1-(2-hydroxyetyl)-2-methyl-5-nitroimidazole] (MTZ). This new assay utilizes the ability of live (surviving) trophozoites to take up oxygen after have been exposed to MTZ. The effect of MTZ on oxygen uptake was compared with its effect on viability as evaluated by a culture method and morphological assays. Oxygen uptake rates decreased in trophozoites treated with MTZ, and this effect was drug concentration dependent: O2 uptake rates went from 3.04 μM O2 min−1 per 106 cells to 0.72 μM O2 min−1 per 106 cells with increasing drug concentration (0.15 to 0.6 mM) in the preincubation. Concentrations of the drug which inhibited oxygen uptake by 28 to 76% in trophozoites killed from 39 to 82% of trophozoites, as evaluated by the culture method, and altered the morphology of 21 to 86% of the trophozoites. Thus, the trophozoites killed by MTZ are nonmotile cells and do not take up oxygen. A good correlation was found between the inhibitory effects of MTZ, as evaluated by oxygen uptake, and cellular viability. Similar 50% inhibitory concentrations were obtained: 0.33 mM by oxygen uptake, 0.26 mM by the culture method, and 0.35 mM by morphological criteria. Oxygen uptake appears to be a good indicator of parasite viability. Therefore, this new method can provide a convenient means to assess MTZ susceptibility in G. lamblia and can be applied for screening potential antigiardial agents.

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Burns, Jacqueline K. "Respiratory Rates and Glycosidase Activities of Juice Vesicles Associated with Section-drying in Citrus". HortScience 25, nr 5 (maj 1990): 544–46. http://dx.doi.org/10.21273/hortsci.25.5.544.

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Oxygen uptake and glycosidase activities were examined in normal and granulated juice vesicles of several citrus fruit. Oxygen uptake was low in normal juice vesicles isolated from freshly harvested `Lee' tangelos [Citrus reticulate Blanco cv. Clementine × (Citrus paradisi Macf. cv. Duncan × Citrus reticulate Blanco cv. Dancy)] and stored `Dancy' tangerine (C. reticulate Blanco) and `Marsh' grapefruit (Citrus paradisi Macf.) (35.7, 17.9, and 11.6 μl O2/hr per g fresh weight, respectively), but was 2- to 3-fold higher in granulated juice vesicles. As severity of granulation increased in grape. fruit, O2 uptake increased. Oxygen uptake in normal and disordered juice vesicles of all citrus fruit examined was reduced to nondetectable levels with 0.1 mM KCN and was insensitive to salicylhydroxamic acid. α - and β -galactosidase and α- and β -glucosidase activities were present in extracts of normal grapefruit juice vesicles (123, 214, 51, and 25 nmol·hr-1·g-1 fresh weight, respectively) and was 2- to 3-fold higher in extracts of granulated tissue. α- and β -mannosidase activities, nondetectable in normal juice vesicle extracts, were present in extracts from granulated tissue. The results suggest that increased metabolic activity occurs in granulated juice vesicles and the energy produced may be used to support cell wall synthesis and modification. Increases in O2 uptake and glycosidase activities correlate well with observed symptoms of section-drying in citrus.

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26

Bell, A. W., J. M. Kennaugh, F. C. Battaglia, E. L. Makowski i G. Meschia. "Metabolic and circulatory studies of fetal lamb at midgestation". American Journal of Physiology-Endocrinology and Metabolism 250, nr 5 (1.05.1986): E538—E544. http://dx.doi.org/10.1152/ajpendo.1986.250.5.e538.

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Uterine and umbilical blood flows, the placental clearance of 3H2O, uterine and umbilical uptakes of oxygen, glucose, and lactate were measured in conscious, pregnant sheep at 71-81 days gestation. Fetal weight was 210 +/- 20 g and less than half placental weight. In relation to fetal weight, umbilical flow was 468 +/- 57 ml X min-1 X kg-1, more than double normal values for the mature fetus. Clearance of 3H2O was approximately 12% of the late pregnancy value but high in relation to fetal weight (280 +/- 23 ml X min-1 X kg-1). Fetal oxygen uptake was 10.9 +/- 0.6 ml X min-1 X kg-1, approximately 40% greater than in late gestation. Umbilical uptake of glucose was also relatively high, whereas lactate uptake was low. Uteroplacental tissues consumed more than 80% of the oxygen and glucose taken up by the pregnant uterus. However, uteroplacental utilization rates of oxygen and glucose as well as net lactate production were lower (approximately 50, 30, and 25%, respectively) than in late pregnancy, despite a larger placental mass (486 +/- 22 vs. 302 +/- 12 g).

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27

Madsen, Peter L., Rasmus Linde, Steen G. Hasselbalch, Olaf B. Paulson i Niels A. Lassen. "Activation-Induced Resetting of Cerebral Oxygen and Glucose Uptake in the Rat". Journal of Cerebral Blood Flow & Metabolism 18, nr 7 (lipiec 1998): 742–48. http://dx.doi.org/10.1097/00004647-199807000-00005.

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In the clinical setting it has been shown that activation will increase cerebral glucose uptake in excess of cerebral oxygen uptake. To study this phenomenon further, this study presents an experimental setup that enables precise determination of the ratio between cerebral uptake of glucose and oxygen in the awake rat. Global CBF was measured by the Kety-Schmidt technique, and the ratio between cerebral uptake rates for oxygen, glucose, and lactate was calculated from cerebral arterial—venous differences. During baseline conditions, rats were kept in a closed box designed to minimize interference. During baseline conditions CBF was 1.08 ± 0.25 mL·g−1·minute−1, and the cerebral oxygen to glucose uptake ratio was 5.5. Activation was induced by opening the sheltering box for 6 minutes. Activation increased CBF to 1.81 mL·g−1·minute−1. During activation cerebral glucose uptake increased disproportionately to cerebral oxygen uptake, and the cerebral oxygen to glucose uptake ratio was 4.2. The accumulated excess glucose uptake during 6 minutes of activation amounted to 2.4 μmol/g. Activation was terminated by closure of the sheltering box. In the postactivation period, the cerebral oxygen to glucose uptake ratio rose to a maximum of 6.4. This response is exactly opposite to the excess cerebral glucose uptake observed during activation.

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28

Casey, E., S. Rishell, B. Glennon i G. Hamer. "Engineering aspects of a mixed methanotrophic culture in a membrane-aerated biofilm reactor". Water Science and Technology 49, nr 11-12 (1.06.2004): 255–62. http://dx.doi.org/10.2166/wst.2004.0855.

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Methanotrophic biodegradation using the membrane-aerated biofilm reactor (MABR) is a technology offering several advantages over both conventional biofilm reactors and suspended-cell processes. In this study the oxidation efficiency of a methanotrophic biofilm in a 1.5 litre MABR was investigated. Measurements of oxygen and methane uptake rates together with biofilm thickness were taken for developing biofilms. It was found that the specific rate of metabolic activity of the biofilm was unusually high as determined by the methane and oxygen uptake rates. Microbial activity stratification was evident and the location of stratified layers of oxygen consuming components of the consortium could be manipulated via the intra-membrane oxygen pressure.

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29

Matsumura, T., H. Yoshihara, R. Jeffs, Y. Takei, S. Nukina, T. Hijioka, R. K. Evans, F. C. Kauffman i R. G. Thurman. "Hormones increase oxygen uptake in periportal and pericentral regions of the liver lobule". American Journal of Physiology-Gastrointestinal and Liver Physiology 262, nr 4 (1.04.1992): G645—G650. http://dx.doi.org/10.1152/ajpgi.1992.262.4.g645.

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The effect of several hormones known to alter intracellular free Ca2+ on rates of O2 uptake in periportal and pericentral regions of the liver lobule was studied in the perfused liver. Regional O2 uptake was measured by stopping the flow and monitoring the decrease in O2 concentration. When perfusion was in the anterograde direction, basal rates of O2 uptake were two to three times higher in periportal than in pericentral regions, and phosphorylase alpha activity, which increases as a function of intracellular free Ca2+ levels, was higher in periportal regions. In contrast, when perfusion was in the retrograde direction, rates of O2 uptake were two to three times greater in pericentral regions. Infusion of epinephrine (0.1 microM) or angiotensin II (5 nM) increased the rate of O2 uptake nearly exclusively in downstream areas of the lobule where O2 tension was low. When perfusions were in the anterograde direction, epinephrine increased phosphorylase alpha activity significantly only in pericentral regions. Stimulation of O2 uptake by epinephrine was blocked by the alpha-adrenergic receptor blocker phentolamine (1 microM) but not by the beta-receptor blocker propranolol. Thus hormones that increase intracellular calcium stimulate O2 uptake predominantly in regions of the liver lobule where O2 tension is lowest, supporting the hypothesis that oxygen tension regulates O2 uptake in the liver via mechanisms involving intracellular free Ca2+.

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30

Stowell, K. M., i K. E. Crow. "The effect of acute ethanol treatment on rates of oxygen uptake, ethanol oxidation and gluconeogenesis in isolated rat hepatocytes". Biochemical Journal 230, nr 3 (15.09.1985): 595–602. http://dx.doi.org/10.1042/bj2300595.

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In hepatocytes isolated from fed rats, acute ethanol pretreatment (at a dose of 5.0 g/kg body wt.) did not change rates of O2 uptake. In cells from starved animals, acute ethanol pretreatment increased O2 uptake by 17-29%. The increased O2 uptake in hepatocytes from starved rats was not accompanied by increased rates of ethanol oxidation, but was accompanied by increased rates of gluconeogenesis under some conditions. The provision of ethanol (10 mM) as a substrate to cells from fed or starved rats decreased O2 uptake in the absence of other substrates or in the presence of lactate, and increased it in the presence of pyruvate or lactate and pyruvate. The results of this study show that the acute effects of ethanol on liver O2 uptake are dependent on the physiological state of the liver. Previously reported large (2-fold) increases in O2 uptake after acute ethanol pretreatment may have been an artefact owing to low control uptake rates (approximately 1.8 micromol/min per g wet wt. of cells) in the liver preparation used. The ATP contents (2.4-2.6 micromol/g wet wt. of cells) and rates of O2 uptake (2.5-5.0 micromol/min per g wet wt. of cells) of cells used in the present study were the same as values reported under conditions close to those in vivo. Therefore the increase in O2 uptake in cells from starved rats after acute ethanol pretreatment is likely to be of physiological significance.

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31

Weyand, Peter G., Cherie S. Lee, Ricardo Martinez-Ruiz, Matthew W. Bundle, Matthew J. Bellizzi i Seth Wright. "High-speed running performance is largely unaffected by hypoxic reductions in aerobic power". Journal of Applied Physiology 86, nr 6 (1.06.1999): 2059–64. http://dx.doi.org/10.1152/jappl.1999.86.6.2059.

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We tested the importance of aerobic metabolism to human running speed directly by altering inspired oxygen concentrations and comparing the maximal speeds attained at different rates of oxygen uptake. Under both normoxic (20.93% O2) and hypoxic (13.00% O2) conditions, four fit adult men completed 15 all-out sprints lasting from 15 to 180 s as well as progressive, discontinuous treadmill tests to determine maximal oxygen uptake and the metabolic cost of steady-state running. Maximal aerobic power was lower by 30% (1.00 ± 0.15 vs. 0.77 ± 0.12 ml O2 ⋅ kg−1 ⋅ s−1) and sprinting rates of oxygen uptake by 12–25% under hypoxic vs. normoxic conditions while the metabolic cost of submaximal running was the same. Despite reductions in the aerobic energy available for sprinting under hypoxic conditions, our subjects were able to run just as fast for sprints of up to 60 s and nearly as fast for sprints of up to 120 s. This was possible because rates of anaerobic energy release, estimated from oxygen deficits, increased by as much as 18%, and thus compensated for the reductions in aerobic power. We conclude that maximal metabolic power outputs during sprinting are not limited by rates of anaerobic metabolism and that human speed is largely independent of aerobic power during all-out runs of 60 s or less.

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32

Terrill, Edward R., i James T. Lewis. "Quantifying Compound Aging Resistance at Service (Ambient) Temperatures". Rubber Chemistry and Technology 82, nr 1 (1.03.2009): 121–30. http://dx.doi.org/10.5254/1.3557003.

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Abstract Oxygen consumption rates were measured on natural rubber compounds with varying levels of a standard antioxidant package. The oxygen consumption rate measurements were performed at temperatures between 20 °C and 80 °C. The results elucidated the mechanism of antioxidants, including their pro-oxidant effects. The pro-oxidant effect dwindled with time. Integrated oxygen uptake results were calculated from repetitive oxygen consumption rate measurements. Integrated oxygen uptake time temperature master curves with empirical shift factors were combined with elongation-tobreak data to monitor the extent of aging. The stability of the compounds at service life temperatures could be quantified by combining the integrated oxygen uptake shift factors with the tensile elongation-to-break data; thereby to produce an elongation-to-break master curve at service life temperatures.

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33

Barstow, T. J., i P. A. Mole. "Linear and nonlinear characteristics of oxygen uptake kinetics during heavy exercise". Journal of Applied Physiology 71, nr 6 (1.12.1991): 2099–106. http://dx.doi.org/10.1152/jappl.1991.71.6.2099.

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We assessed the linearity of oxygen uptake (VO2) kinetics for several work intensities in four trained cyclists. VO2 was measured breath by breath during transitions from 33 W (baseline) to work rates requiring 38, 54, 85, and 100% of maximal aerobic capacity (VO2max). Each subject repeated each work rate four times over 8 test days. In every case, three phases (phases 1, 2, and 3) of the VO2 response could be identified. VO2 during phase 2 was fit by one of two models: model 1, a double exponential where both terms begin together close to the start of phase 2, and model 2, a double exponential where each of the exponential terms begins independently with separate time delays. VO2 rose linearly for the two lower work rates (slope 11 ml.min-1 W-1) but increased to a greater asymptote for the two heavier work rates. In all four subjects, for the two lighter work rates the double-exponential regression reduced to a single value for the time constant (average across subjects 16.1 +/- 7.7 s), indicating a truly monoexponential response. In addition, one of the responses to the heaviest work rate was monoexponential. For the remaining seven biexponential responses to the two heaviest work rates, model 2 produced a significantly better fit to the responses (P less than 0.05), with a mean time delay for the slow component of 105 +/- 46 s.(ABSTRACT TRUNCATED AT 250 WORDS)

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34

Marsden, Islay D., Sandra E. Shumway i Dianna K. Padilla. "Does size matter? The effects of body size and declining oxygen tension on oxygen uptake in gastropods". Journal of the Marine Biological Association of the United Kingdom 92, nr 7 (3.11.2011): 1603–17. http://dx.doi.org/10.1017/s0025315411001512.

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Metabolic rate is one of the most frequently measured physiological variables and the relationship between oxygen uptake and body mass is one of the most controversial issues in biology. The present study used closed chamber respirometry to compare the oxygen uptake of 32 species of benthic British gastropod molluscs of a wide size-range (from less than 0.001 g to greater than 10 g dry tissue weight). We investigated the effects of body size on the respiratory rate at 10°C to explore the evolutionary and phylogenetically determined patterns of metabolic scaling both among different gastropods groups, and within siphonate and asiphonate caenogastropods. Resting oxygen uptake (O2) increased with body mass (W) with a slope value of 0.6 using both ordinary least squares (OLS) and standard major axis (SMA) where N = 488, over a 6 fold range of body mass. The slopes b of the regression lines relating oxygen uptake to body mass were similar for all heterobranch molluscs and most caenogastropods. Highest mass-specific rates for oxygen consumption were found for the smallest littorinid species. Trophic mode significantly affected the amount of oxygen consumed with higher oxygen uptake in herbivores than other groups, including detritivores and predators. All of the gastropods reduced their oxygen consumption when exposed to declining oxygen conditions; however, about a third of the species exhibited partial regulation at higher oxygen partial pressures. When exposed to 20% normal saturation levels, smaller gastropods respired at approximately 25% of their rates in fully saturated seawater whereas larger species (above 0.1 g dry tissue weight) respired at approximately 35% of the values recorded at full saturation. Our study suggests that a scaling exponent relating O2 to body mass of 0.6 is typical and may be ‘universal’ for gastropods. It is below the 0.75 scaling exponent which has been proposed for ectothermic invertebrates. It is concluded that size does matter in determining the metabolic patterns of gastropods and that the quantity of oxygen consumed and the energy balance of gastropods is affected by activity, food type and exposure to declining oxygen conditions.

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35

Ye, Ji-Ming, Eric Q. Colquhoun, Manthinda Hettiarachchi i Michael G. Clark. "Flow-induced oxygen uptake by the perfused rat hindlimb is inhibited by vasodilators and augmented by norepinephrine: a possible role for the microvasculature in hindlimb thermogenesis". Canadian Journal of Physiology and Pharmacology 68, nr 1 (1.01.1990): 119–25. http://dx.doi.org/10.1139/y90-018.

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Oxygen uptake in the perfused rat hindlimb was studied at 25 °C using an artificial perfusate, and the effects of perfusate flow rate, norepinephrine, and vasodilators were compared. Hindlimb oxygen uptake and perfusion pressure each increased as the flow rate was increased stepwise from 2 to 18.5 mL/min per hindlimb. At each flow rate, the rate of oxygen uptake was inhibited by the vasodilator nitroprusside (0.5 mM) and increased by norepinephrine (5 nM). A corresponding change in perfusion pressure also occurred, with norepinephrine leading to a marked increase and nitroprusside leading to a decrease; however, changes in oxygen uptake and pressure were not linearly related. The lactate/pyruvate ratio of the perfusate was used as an index of tissue perfusion and was determined at each flow rate. Lactate and pyruvate efflux increased as the flow rate was increased stepwise from 2 to 18.5 mL/min per hindlimb. At 2 mL/min per hindlimb, the lactate/pyruvate ratio was 15; at flow rates equal or greater than 4 mL/min per hindlimb, the ratio was constant at 9. Nitroprusside had no significant effect on the ratio at any flow rate even though a marked inhibitory effect on oxygen uptake was evident. Muscle content of high energy phosphates at 8 mL/min per hindlimb did not differ before and after treatment with vasodilators. In addition, the vasodilators had no apparent effect on skeletal muscle oxygen uptake or force development during electrical stimulation. The findings indicate that oxygen uptake by the hindlimb is not limited by inadequate perfusion and that oxygen uptake can be further increased by norepinephrine. The close association of the vasoconstrictive action of norepinephrine with the increase in oxygen uptake and the finding that the increase in oxygen uptake is minimal when nitroprusside is present suggest a central role of the vasculature in the control of muscle thermogenesis. The novel possibility that a significant proportion of oxygen uptake by the resting hindlimb is a consequence of the work done by cells contributing to vasoconstriction (i.e., thermogenesis from "hot pipes") is discussed.Key words: hindlimb oxygen uptake, oxygen uptake and vasoconstriction, norepinephrine, pressure-induced oxygen uptake, nitroprusside.

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36

Elberling, Bo, i Bjarne Riis Langdahl. "Note: Natural heavy-metal release by sulphide oxidation in the High Arctic". Canadian Geotechnical Journal 35, nr 5 (1.10.1998): 895–901. http://dx.doi.org/10.1139/t98-047.

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An assessment of the environmental impact of the weathering of sulphide-rich rocks at Citronen Fjord, North Greenland, provided information on sulphide oxidation rates and metal release from outcrops of sediment-hosted, stratiform ore that may be mined for its zinc content. In situ oxygen uptake rates were measured at the surface of partly weathered sulphide-rich outcrops and compared with metal contents in streams and soil water. The oxygen uptake rates measured during August 1996 were of the same order of magnitude as those reported from mine tailings at lower latitudes. The variation in metal concentrations and pH of the drainage waters reflects the spatial variation in sulphide oxidation and carbonate buffering. High weathering rates of sulphide minerals occur in the High Arctic during the summer, and release of heavy metals must be considered a potential environmental issue if mining is initiated.Key words: sulphide oxidation, pyrite, sphalerite, oxygen, High Arctic, zinc.

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37

Miller, FC, ER Harper i BJ Macauley. "Field examination of temperature and oxygen relationships in mushroom composting stacks dash consideration of stack oxygenation based on utilisation and supply". Australian Journal of Experimental Agriculture 29, nr 5 (1989): 741. http://dx.doi.org/10.1071/ea9890741.

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Temperature and oxygen concentration in Phase I composting stacks were investigated in the field. that both determine and are consequences of biological Investigations focused on various physical factors activity. Data indicate that oxygen concentrations in Phase I stacks are affected by convection, gaseous diffusion and utilisation rates, but that these rates vary significantly spatially and temporally. When stack temperatures exceed 60�C, biological rates of activity, and therefore oxygen uptake, decrease, allowing oxygen to penetrate well into the centres of stacks. While natural convection is commonly used to explain stack oxygenation, this is an over simplification that does not adequately describe stack oxygen concentrations.

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38

Takala, Teemu O., Pirjo Nuutila, Chietsugu Katoh, Matti Luotolahti, Jörgen Bergman, Maija Mäki, Vesa Oikonen i in. "Myocardial blood flow, oxygen consumption, and fatty acid uptake in endurance athletes during insulin stimulation". American Journal of Physiology-Endocrinology and Metabolism 277, nr 4 (1.10.1999): E585—E590. http://dx.doi.org/10.1152/ajpendo.1999.277.4.e585.

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We have previously demonstrated reduced myocardial glucose uptake rates in hearts of endurance athletes, which could be due to increased use of alternative fuels or reduced energy demands. In the present study myocardial blood flow, oxygen consumption, and free fatty acid uptake were measured with [15O]H2O, [15O]O2, [18F]FTHA, and positron emission tomography (PET) in 9 endurance athletes and 11 sedentary men during euglycemic hyperinsulinemia. Compared with sedentary men, athletes had 33% lower myocardial blood flow, 27% lower oxygen consumption, and 20% lower estimated myocardial work per gram of tissue. Myocardial fatty acid uptake rates were not significantly different in endurance athletes (0.83 ± 0.29) and sedentary men (1.0 ± 0.31 μmol ⋅ 100 g−1 ⋅ min−1, P = 0.232). In conclusion, myocardial blood flow and oxygen consumption per unit mass of myocardium are reduced at rest in endurance athletes. This can be explained by reduced energy requirements per gram of tissue due to anatomic and physiological changes of the athlete’s heart.

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39

Schulz, Heide N., i Dirk de Beer. "Uptake Rates of Oxygen and Sulfide Measured with Individual Thiomargarita namibiensis Cells by Using Microelectrodes". Applied and Environmental Microbiology 68, nr 11 (listopad 2002): 5746–49. http://dx.doi.org/10.1128/aem.68.11.5746-5749.2002.

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ABSTRACT Gradients of oxygen and sulfide measured towards individual cells of the large nitrate-storing sulfur bacterium Thiomargarita namibiensis showed that in addition to nitrate oxygen is used for oxidation of sulfide. Stable gradients around the cells were found only if acetate was added to the medium at low concentrations.

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40

Weng, Dong Chen, Yong Zhen Peng, Xiao Xia Wang, Zhi Jia Miao i Gui Song Xue. "Inhibition of Nitrite on Denitrifying Phosphate Removal Process". Advanced Materials Research 955-959 (czerwiec 2014): 1944–50. http://dx.doi.org/10.4028/www.scientific.net/amr.955-959.1944.

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Poly-phosphate accumulating organisms (PAOs) could use nitrite as electron acceptor but poorly function compared to oxygen in phosphorus removal. The authors try to figure out the different effects on anoxic and aerobic P-uptake by environmental factors (pH, temperature and nitrite concentration) and identify the real inhibitor in anoxic metabolisms. 26 sets of batch tests were designed, using highly concentrated PAO cultures. The results show pH influence on P-uptake activity are similar in anoxic and aerobic tests, but temperature has strong effects on aerobic P-uptake activity compared to anoxic. pH values were are correlated linearly with nitrite reduction and P-uptake rates instead of FNA. Also, weak correlation between FNA and two reaction rates shows pH rather than FNA is likely the main inhibitor. P-uptake rates are correlated linearly with nitrite reduction and PHA consumption rates. It’s possible that intracellar concentration isn’t affected by FNA diffusion and don’t affect intracellar P-uptake process.

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41

Aidun, Bijan, i Daniel W. Smith. "Design and evaluation of an automated oxygen uptake rate measurement system". Canadian Journal of Civil Engineering 15, nr 6 (1.12.1988): 1015–21. http://dx.doi.org/10.1139/l88-133.

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The design and operating procedure for a newly developed automatic oxygen uptake rate (OUR) measurement apparatus is presented. This unit, with the aid of a microcomputer, is capable of collecting a volume of sample, aerating the sample, measuring the oxygen concentration at preselected times, and calculating the oxygen uptake rate on a routine basis. The OUR unit was evaluated using three different performance testing procedures. These were (1) a calibration and general performance test, (2) a long-term performance test, and (3) a detailed comparative performance test. The results of each of these tests are presented. The value and alternative uses of routine monitoring of OUR are discussed along the possible applications such as detection of toxic compounds entering the plant and adjustment of sludge return rates to match OUR values. Key words: oxygen uptake rate, activated sludge, microcomputer, process control, oxygen consumption.

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42

Ritz, D. A., E. G. Foster i K. M. Swadling. "Benefits of swarming: mysids in larger swarms save energy". Journal of the Marine Biological Association of the United Kingdom 81, nr 3 (czerwiec 2001): 543–44. http://dx.doi.org/10.1017/s0025315401004210.

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Mysids have previously been shown to consume oxygen at much lower rates when in a swarm (cohesive group in which individuals are evenly spaced but not polarized) than when in uncohesive small groups. Thus the swarm represents a strategy for conserving energy. In this study different swarm sizes of mysids were forced to perform escape responses by exposing them to jets of ammonium hydroxide, while measuring their oxygen uptake. Swarms of 200 individuals showed no significant difference in oxygen consumption with or without the ammonium treatment. In contrast, swarms of 100 showed a significant increase of around 45% oxygen uptake when exposed to ammonium. In conjunction with earlier demonstrations of increased feeding success and lower oxygen uptake when aggregated, this work clearly confirms the energetic benefits of being in a larger social group rather than a smaller one or remaining solitary.

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43

McGee, Georgia Evelyn, i Timothy Darren Clark. "All puffed out: do pufferfish hold their breath while inflated?" Biology Letters 10, nr 12 (grudzień 2014): 20140823. http://dx.doi.org/10.1098/rsbl.2014.0823.

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The inflation response of pufferfishes is one of the most iconic predator defence strategies in nature. Current dogma suggests that pufferfish inflation represents a breath-holding response, whereby gill oxygen uptake ceases for the duration of inflation and cutaneous respiration increases to compensate. Here, we show that the black-saddled pufferfish ( Canthigaster valentini ) has an excellent capacity for oxygen uptake while inflated, with uptake rates increasing to five-times that of resting levels. Moreover, we show that this species has negligible capacity for cutaneous respiration, concluding that the gills are the primary site of oxygen uptake while inflated. Despite this, post-deflation recovery of aerobic metabolism took an average of 5.6 h, suggesting a contribution of anaerobic metabolism during pre-inflation activity and during the act of ingesting water to achieve inflation.

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Gervais, Connor R., i Culum Brown. "Impact of conspecific necromones on the oxygen uptake rates of a benthic elasmobranch". Animal Behaviour 174 (kwiecień 2021): 1–8. http://dx.doi.org/10.1016/j.anbehav.2021.01.009.

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45

Cathalot, C., C. Rabouille, L. Pastor, B. Deflandre, E. Viollier, R. Buscail, C. Treignier i A. Pruski. "Seasonal dynamics of carbon recycling in coastal sediments influenced by rivers: assessing the impact of flood inputs in the Rhône River prodelta". Biogeosciences Discussions 6, nr 6 (17.11.2009): 10775–816. http://dx.doi.org/10.5194/bgd-6-10775-2009.

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Abstract. The biogeochemical fate of the particulate organic inputs from the Rhône River was studied on a seasonal basis by measuring sediment oxygen uptake rates in the prodelta, both during normal and flood regimes. On a selected set of 10 stations in the prodelta and nearby continental shelf, in situ and laboratory measurements of sediment oxygen demand were performed in early spring and summer 2007 and late spring and winter 2008. In and ex situ sediment Diffusive Oxygen Uptakes (DOU) did not show any significant differences except for shallowest organic rich stations. DOU rates show highest values concentrated close to the river mouth (approx. 20 mmol O2 m-2 d-1) and decrease offshore to values around 4.5 mmol O2 m-2 d-1 preferentially in a south west direction, most likely as the result of the preferential transport of the finest riverine material. Total Oxygen Uptake (TOU) obtained from core incubation showed the same spatial pattern with an averaged TOU/DOU ratio of 1.2± 0.4. Over different seasons, spring summer and late fall, benthic mineralization rates presented this same stable spatial pattern. A flood of the Rhône River occurred in June 2008 and brought up to 30 cm of new soft muddy deposit. Right after this flood, sediment DOU rates close to the river mouth dropped from around 15–20 mmol O2 m-2 d-1 to values close to 10 mmol O2 m-2 d-1, in response to the deposition near the river outlet of low reactivity organic matter associated to fine material. Six months later, the oxygen distribution had relaxed back to its initial stage: the initial spatial distribution was found again underlining the active microbial degradation rates involved and the role of further deposits. These results highlight the rapid response to flood deposits in prodeltaic areas which may act as a suboxic sediment reactor and shorten the relaxation time.

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46

Orupõld, K., K. Hellat i T. Tenno. "Estimation of treatability of different industrial wastewaters by activated sludge oxygen uptake measurements". Water Science and Technology 40, nr 1 (1.07.1999): 31–36. http://dx.doi.org/10.2166/wst.1999.0008.

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The activated sludge short-term respiration measurement is proposed for assessing the properties of activated sludge and biological treatability of wastewaters. Different influents to the wastewater treatment plant were analyzed and compared on the basis of exogenous oxygen uptake rates of activated sludge. The kinetic parameters of biodegradation processes were determined by monitoring the degradation-associated oxygen consumption in tests with different amounts of wastewaters from textile industries and tanneries. The short-term oxygen demands in the tests formed 25-45% of the biochemical oxygen demand of the textile industry wastewater.

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47

Parra, Gema, Roger Villanueva i Manuel Yúfera. "Respiration rates in late eggs and early hatchlings of the common octopus, Octopus vulgaris". Journal of the Marine Biological Association of the United Kingdom 80, nr 3 (czerwiec 2000): 557–58. http://dx.doi.org/10.1017/s0025315400002319.

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Respiration rates during late embryonic development and hatchlings of Octopus vulgaris were measured at 20 °C. Oxygen consumption rates increased suddenly at hatching, in response to the increase in energetic expenditure due to their constant swimming activity by means of jet propulsion. Estimates indicate that hatchlings consumed three times more oxygen than the embryos at late stages. Chemical composition analysis revealed a relatively high nitrogen content (11%) in O. vulgaris hatchlings with an energy content of 1.09±0.03 J mg dry matter−1. Specific oxygen consumption in unfed O. vulgaris hatchlings reached values around 0.18 nmol O2 μg−1 h−1. It was estimated that the oxygen consumption of a medium-size egg mass of O. vulgaris is approximately twice than the oxygen uptake of the respective brooding female.

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Qu, Wei, Lee M. Graves i Ronald G. Thurman. "PGE2 stimulates O2 uptake in hepatic parenchymal cells: involvement of the cAMP-dependent protein kinase". American Journal of Physiology-Gastrointestinal and Liver Physiology 277, nr 5 (1.11.1999): G1048—G1054. http://dx.doi.org/10.1152/ajpgi.1999.277.5.g1048.

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The aim of this study was to determine which PGE2 receptors and signal transduction pathways are responsible for the stimulation of oxygen uptake in liver. Hepatic parenchymal cells isolated from female Sprague-Dawley rats were incubated either with PGE2, 17-phenyl-omega-trinor PGE2 (an EP1-specific agonist), or 11-deoxy PGE1 (an EP2/EP4-specific agonist), and oxygen consumption was measured. Both PGE2 and 11-deoxy PGE1 stimulated oxygen consumption. However, an EP1agonist was without effect. Although PGE2 elevated intracellular calcium, this occurred at concentrations ∼500-fold lower than that required to stimulate oxygen uptake. PGE2-stimulated increases in cAMP formation correlated well with the increase in oxygen consumption. Dibutyryl cAMP also increased oxygen consumption. Furthermore, N-[2-( p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide, a cell-permeable inhibitor of protein kinase A (PKA), reduced the stimulation of oxygen uptake by PGE2. Incubation of isolated parenchymal cell mitochondria with the purified catalytic subunit of PKA and ATP increased both state 3 rates of oxygen uptake and the respiratory control ratio by ∼50%. Activation of these events was prevented by incubation with the PKA inhibitory peptide, PKI. These findings are consistent with the hypothesis that PGE2 stimulates oxygen consumption via an EP2 and/or EP4 subclass of receptors through the actions of cAMP on a cAMP-dependent protein kinase.

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Gonzalez, R., i D. Mcdonald. "THE RELATIONSHIP BETWEEN OXYGEN UPTAKE AND ION LOSS IN FISH FROM DIVERSE HABITATS". Journal of Experimental Biology 190, nr 1 (1.05.1994): 95–108. http://dx.doi.org/10.1242/jeb.190.1.95.

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A recent examination of the relationship between O2 uptake (M(dot)O2) and diffusive sodium loss (JNaout) in a freshwater fish showed that Na+ losses after exhaustive exercise exceeded those expected on the basis of M(dot)O2, probably due to distortion of the paracellular tight junctions (the primary site of diffusive ion loss) and/or glomerular-type filtration caused by increased lamellar pressure. In the present study, an examination of this relationship in nine species of fish from diverse habitats supports this model. Under routine conditions, the rate of Na+ loss per unit of O2 consumed (termed the ion/gas ratio or IGR) was similar in all the species tested, averaging 61.6 pmol Na+ nmol-1 O2. After exhaustive exercise, the degree to which the IGR of each species increased relative to its routine levels (post-exercise IGR/routine IGR) was exponentially related to the relative rise in M(dot)O2, i.e. greater rates of O2 uptake led to even greater ion losses. Further analysis revealed that, although naturally active species had the lowest proportionate increase in M(dot)O2, by virtue of their high routine rates, they had the highest post-exercise rates of O2 uptake. In fact, there was an inverse correlation between post-exercise IGR and M(dot)O2, i.e. species with low M(dot)O2 values lost more Na+ per mole of O2 taken up than did species with high ones. Thus, naturally active species, such as the common and golden shiner, were able to achieve higher rates of O2 uptake while avoiding high rates of ion loss. Surprisingly, species such as banded sunfish, yellow perch and smallmouth bass did not limit ion loss associated with exercise despite their apparent ability to do so. They demonstrated a strong ability to limit ion losses caused by a brief osmotic shock and by exposure to soft water (both of which distort tight junctions).

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Stathokostas, Liza, John M. Kowalchuk, Robert J. Petrella i Donald H. Paterson. "Moderate and heavy oxygen uptake kinetics in postmenopausal women". Applied Physiology, Nutrition, and Metabolism 34, nr 6 (grudzień 2009): 1065–72. http://dx.doi.org/10.1139/h09-107.

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The lack of estrogen in postmenopausal women not using hormone replacement therapy (HRT), compared with those using HRT, may reduce submaximal blood flow during exercise and result in an oxygen delivery limitation constraining oxygen uptake (VO2) kinetics. The adaptation of pulmonary VO2 (VO2p) during the transition to exercise in older women was examined in this study. Thirty-one healthy postmenopausal women (mean age, 61 ± 6 years), 15 not using HRT and 16 using HRT, performed repeated exercise transitions (6 min) on a cycle, to work rates corresponding to 80% of estimated ventilatory threshold (moderate-intensity exercise) and to Δ50 (heavy-intensity exercise). There was no difference in moderate-intensity τVO2p between non-HRT (40 ± 9 s) and HRT (41 ± 9 s) women. Similarly, there was no difference in heavy-intensity τVO2p between non-HRT (44 ± 8 s) and HRT (45 ± 8 s) women. Thus, HRT did not affect the slowing of VO2 kinetics of older women.

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