The Influence of Oxygen Tension Upon the Respiration of Unicellular Organisms

Amberson, William R.

doi:10.2307/1537151

Cited by 65 publications

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“…For large partial pressures ( P c ≫ K m ), the consumption rate is independent of oxygen partial pressure. Nonlinear Monod oxygen consumption is observed in many living organisms 13–15, 20, 21. For humans, Bonanno et al8 have established that oxygen consumption increases with rising oxygen tension, consistent with Monod kinetics, which is illustrated by the solid line in Figure 4.…”

Section: Methodsmentioning

confidence: 71%

“…Moreover, inclusion of Monod kinetics avoids aphysical oxygen tensions in the cornea obtained by assuming the oxygen‐consumption rate as constant 7. Oxygen partial pressure for reaching 90% of the saturation oxygen‐consumption rate for various organisms is in the range 12–25 mmHg 13–15, 20, 21. Therefore, we set K m = 2.2 mmHg from Eq.…”

Section: Methodsmentioning

confidence: 99%

“…This technique provides a simple, fast, reliable, and noninvasive way to obtain Q c by wearing a soft contact lens for a few minutes 8. Unfortunately, the current mathematical framework used to obtain Q c from the measured tear‐film oxygen tension is not satisfactory because the oxygen‐consumption rate is assumed constant throughout the cornea; the oxygen‐consumption rate, however, is known to be a nonlinear function of local oxygen tension in biological tissues and organisms 13–21. Further, the corneal oxygen permeability ( D c k c ) needed for obtaining human Q c was measured on rabbits for two corneal layers: endothelium and epithelium 8, 22, 23.…”

Section: Introductionmentioning

confidence: 99%

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Diffusion and Monod kinetics to determine in vivo human corneal oxygen‐consumption rate during soft contact‐lens wear

2008

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The rate of oxygen consumption is an important parameter to assess the physiology of the human cornea. Metabolism of oxygen in the cornea is influenced by contact-lens-induced hypoxia, diseases such as diabetes, surgery, and drug treatment. Therefore, estimation of in vivo corneal oxygen-consumption rate is essential for gauging adequate oxygen supply to the cornea. Phosphorescence quenching of a dye coated on the posterior of a soft contact lens provides a powerful technique to measure tear-film oxygen tension (Harvitt and Bonanno, Invest Ophthalmol Vis Sci 1996;37:1026-1036; Bonanno et al., Invest Ophthalmol Vis Sci 2002;43:371-376). Unfortunately, previous work in establishing oxygen-consumption kinetics from transient postlens tear-film oxygen tensions relies on the simplistic assumption of a constant corneal-consumption rate. A more realistic model of corneal metabolism is needed to obtain reliable oxygen-consumption kinetics. Here, physiologically relevant nonlinear Monod kinetics is adopted for describing the local oxygen-consumption rate, thus avoiding aphysical negative oxygen tensions in the cornea. We incorporate Monod kinetics in an unsteady-state reactive-diffusion model for the cornea contact-lens system to determine tear-film oxygen tension as a function of time when changing from closed-eye to open-eye condition. The model was fit to available experimental data of in vivo human postlens tear-film oxygen tension to determine the corneal oxygen-consumption rate. Reliance on corneal oxygen diffusivity and solubility data obtained from rabbits is no longer requisite. Excellent agreement is obtained between the proposed model and experiment. We calculate the spatial-averaged in vivo human maximum corneal oxygen-consumption rate as Q(c)(max) = 1.05 x 10(-4) mL/(cm(3) s). The calculated Monod constant is K(m) = 2.2 mmHg.

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Section: Methodsmentioning

confidence: 71%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Diffusion and Monod kinetics to determine in vivo human corneal oxygen‐consumption rate during soft contact‐lens wear

2008

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“…If we take the extreme values of 12 or 25 mmHg for the oxygen partial pressure (Shoup, 9 Amberson, 10 Fatt, 11 Tang, 12 Takahashi et al 13 ), other values for K m could have been possible. Nevertheless, the Chhabra's value for K m tends to be an estimated average value, and in this way it may be perfectly acceptable.…”

Section: Methodsmentioning

confidence: 99%

Diffusion and Monod kinetics model to determine in vivo human corneal oxygen-consumption rate during soft contact lens wear

Castillo

Silva

Hernández

et al. 2015

Journal of Optometry

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“…Cleavage rate, however, is not necessarily limitedby the rate of 02 consumption per se in a number of forms. For example, Amberson (1928) found the cleavage rate was not retarded seriously in Arbacia eggs, when 02 pressure was diminished, until the pressure reduction was sufficient to decrease the 02 consumption to about half normal. My findings agree with this generality in so far as cleavage was not completely inhibited otherwise.…”

Section: O Effects Of Caffeine On Fertilized Sea Urchin Eggmentioning

confidence: 99%

The Effects of Caffeine on Oxygen Consumption and Cell Division in the Fertilized Egg of the Sea Urchin, Arbacia Punctulata

Cheney

1945

Journal of General Physiology

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1. By means of the Warburg-Barcroft microrespirometer apparatus and the Warburg direct method, the relative effect of caffeine upon the O2 consumption of the fertilized egg of Arbacia punctulata was shown for the following concentrations in sea water: 0.002 per cent (M/10,000), 0.004 per cent (M/5,000), 0.02 per cent (M/1,000), 0.1 per cent (M/200), 0.2 per cent (M/100), 0.5 per cent (M/40), and 2 per cent (M/10). 2. In comparison with the normal eggs (uninhibited, non-caffeine-treated controls), caffeine in concentrations including and greater than 0.1 per cent (M/200) depressed the average uptake from approximately 25 to 61 per cent over the 3 hour period. In a number of instances, as typified by Experiment 10, the effective inhibitory concentration ranged from 0.02 per cent (M/1,000) upward and the degree of depression of the O2 consumption ranged from 10.6 per cent to 60.6 per cent. 3. All caffeine concentrations including and above 0.02 per cent (M/1,000) in the series used, resulted in decreasing the normal rate of cleavage division in the fertilized Arbacia eggs. 4. The higher concentrations (0.5 and 2 per cent) produced a complete blockage of the cleavage process. 5. Complete cleavage inhibition was noted only when the O2 uptake had been depressed to 50 per cent or more of the normal controls. 6. O2 consumption-time relationship data indicate an average depression, in O2 consumption over a 3 hour period, ranging from 25 per cent with a caffeine concentration of 0.1 per cent to a 61 per cent inhibition with a concentration of 2 per cent. 7. Concentrations of less than 0.1 per cent (certainly of less than 0.02 per cent) give variable results and indicate no significant effect. 8. It is inferred from the respiration data presented that it is probable that the inhibition of the O2 consumption in fertilized Arbacia eggs is due to the influence of caffeine upon the main (activity or primary) pathway. It will be observed that there are certain similarities of the caffeine data to the degree of inhibition accomplished by sodium cyanide. Moreover, it has been demonstrated that the cyanide probably acts on the cytochrome oxidase step in the cytochrome oxidase-cytochrome chain of reactions constituting the O2 uptake phase of respiratory metabolism. It is not improbable, therefore, that caffeine also may act upon the cytochrome oxidase enzyme. 9. From the viewpoint of environmental conditions influencing reproductive phenomena, it is of interest that caffeine can affect the normal metabolism of the zygote.

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The Influence of Oxygen Tension Upon the Respiration of Unicellular Organisms

Cited by 65 publications

References 0 publications

Diffusion and Monod kinetics to determine in vivo human corneal oxygen‐consumption rate during soft contact‐lens wear

Diffusion and Monod kinetics to determine in vivo human corneal oxygen‐consumption rate during soft contact‐lens wear

Diffusion and Monod kinetics model to determine in vivo human corneal oxygen-consumption rate during soft contact lens wear

The Effects of Caffeine on Oxygen Consumption and Cell Division in the Fertilized Egg of the Sea Urchin, Arbacia Punctulata

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