A case of unusually high oxygen demand in a eutrophic lake

Hydrobiologia ◽  
1991 ◽  
Vol 209 (3) ◽  
pp. 235-243 ◽  
Author(s):  
Harjeet S. Sehgal ◽  
Eugene B. Welch
Keyword(s):  
Oxygen Demand ◽  
Eutrophic Lake ◽  
High Oxygen ◽  
High Oxygen Demand

scholarly journals Hypoferremia predicts hospitalization and oxygen demand in COVID-19 patients

2020 ◽  
Author(s):  
Theresa Hippchen ◽  
Sandro Altamura ◽  
Martina U. Muckenthaler ◽  
Uta Merle
Keyword(s):  
Iron Metabolism ◽  
Serum Iron ◽  
Iron Concentration ◽  
Oxygen Demand ◽  
Multivariate Regression Analysis ◽  
High Oxygen ◽  
University Hospital ◽  
List Type ◽  
Inflammatory Parameters ◽  
High Oxygen Demand

ABSTRACTBackgroundIron metabolism might play a crucial role in cytokine release syndrome in COVID-19 patients. Therefore we assessed iron metabolism markers in COVID-19 patients for their ability to predict disease severity.MethodsCOVID-19 patients referred to the Heidelberg University Hospital were retrospectively analyzed. Patients were divided into outpatients (cohort A, n=204), inpatients (cohort B, n=81), and outpatients later admitted to hospital because of health deterioration (cohort C, n=23).ResultsIron metabolism parameters were severely altered in patients of cohort B and C compared to cohort A. In multivariate regression analysis including age, gender, CRP and iron-related parameters only serum iron and ferritin were significantly associated with hospitalization. ROC analysis revealed an AUC for serum iron of 0.894 and an iron concentration <6µmol/l as the best cutoff-point predicting hospitalization with a sensitivity of 94.7% and a specificity of 67.9%. When stratifying inpatients in a low- and high oxygen demand group serum iron levels differed significantly between these two groups and showed a high negative correlation with the inflammatory parameters IL-6, procalcitonin, and CRP. Unexpectedly, serum iron levels poorly correlate with hepcidin.ConclusionWe conclude that measurement of serum iron can help predicting the severity of COVID-19. The differences in serum iron availability observed between the low and high oxygen demand group suggest that disturbed iron metabolism likely plays a causal role in the pathophysiology leading to lung injury.KEY POINTSIron metabolism parameters are severely altered in COVID-19 patients.Measurement of serum iron can help predicting the severity of COVID-19.

Perfusion-independent oxygen extraction in myoglobin-rich hearts

1988 ◽  
Vol 135 (1) ◽  
pp. 301-315
Author(s):  
J. R. Bailey ◽  
W. R. Driedzic
Keyword(s):  
Oxygen Consumption ◽  
Flow Rate ◽  
Oxygen Demand ◽  
High Oxygen ◽  
Oxygen Extraction ◽  
Oxidizing Agent ◽  
Flow Rates ◽  
Sea Raven ◽  
High Oxygen Demand

Cardiac myoglobin plays a role in oxygen consumption and has a protective effect during periods of hypoxia, but little is known about the role of myoglobin during periods of ischaemia. Myoglobin-rich sea raven hearts and myoglobin-poor ocean pout hearts were isolated and perfused at varying flow rates and under conditions of low and high oxygen demand to assess the role of myoglobin in oxygen extraction. In the myoglobin-rich hearts, oxygen extraction remained constant over the flow range. In the myoglobin-poor hearts, oxygen extraction was significantly elevated, relative to controls, at the lower flow rates but decreased as the flow rate increased. In hearts where myoglobin was inactivated by an oxidizing agent, oxygen extraction was similar to that observed in myoglobin-poor hearts. Under conditions of high oxygen demand, myoglobin-rich hearts again showed a constant oxygen extraction over the flow range. Myoglobin-inactivated hearts had a significantly elevated oxygen extraction at low flows, and this decreased as flow rate increased. These data suggest that myoglobin renders oxygen extraction by fish hearts independent of the rate of perfusion.

Use of Naso-Tracheal Oxygen Catheter During Bronchoscopy in Patients With High Oxygen Demand

CHEST Journal ◽  
2013 ◽  
Vol 144 (4) ◽  
pp. 802A
Author(s):  
Justin Thomas ◽  
Michael Galloway ◽  
Ali Musani
Keyword(s):  
Oxygen Demand ◽  
High Oxygen ◽  
High Oxygen Demand

The opto-respiratory compromise: Balancing oxygen supply and light transmittance in the retina

Physiology ◽  
2021 ◽  
Author(s):  
Christian Damsgaard ◽  
Michael William Country
Keyword(s):  
Blood Vessels ◽  
Oxygen Supply ◽  
Oxygen Demand ◽  
Blood Perfusion ◽  
High Oxygen ◽  
Light Transmittance ◽  
Light Path ◽  
Respiratory Compromise ◽  
High Oxygen Demand ◽  
Physiological Systems

The light-absorbing retina has an exceptionally high oxygen demand, which imposes two conflicting needs: high rates of blood perfusion and an unobstructed light path devoid of blood vessels. This review discusses mechanisms and physiological tradeoffs underlying retinal oxygen supply in vertebrates and examines how these physiological systems supported the evolution of vision.

A high oxygen demand in normal tension glaucoma

2015 ◽  
Vol 93 ◽  
pp. n/a-n/a
Author(s):  
C. Turksever ◽  
M. Todorova ◽  
S. Orguel
Keyword(s):  
Oxygen Demand ◽  
Normal Tension Glaucoma ◽  
High Oxygen ◽  
High Oxygen Demand

Comparison of mayfly (Ephemeroptera) taxocenes of permanent and intermittent Central European small streams via species traits

Biologia ◽  
2010 ◽  
Vol 65 (4) ◽  
Author(s):  
Pavla Řezníčková ◽  
Tomáš Soldán ◽  
Petr Pařil ◽  
Světlana Zahrádková
Keyword(s):  
Global Climate ◽  
Extreme Temperature ◽  
Oxygen Demand ◽  
Hydrological Regime ◽  
Species Traits ◽  
Individual Species ◽  
Biological Traits ◽  
Small Streams ◽  
High Oxygen Demand ◽  
The Impact

AbstractThe recurrent drying out of small streams in past decades has shown an urgent need to pay attention to the impact of global climate change. The objectives of this study were to describe the effect of drying out on the composition of the mayfly taxocene and evaluate the relevance of individual species traits for survival of mayflies to drying out. The mayfly taxocenes of two model localities, one at an intermittent and one at a permanent brook, were investigated in 2002, 2003 and 2005. Compared with the permanent stream, the taxocene of the intermittent stream was short of nine species, foremost rheobionts and high oxygen demand species. To explain further differences between both stream types in survival and recolonisation ability, 15 species traits were evaluated. These included so-called “ecological traits” (e.g., habitat and substrate range, density, distribution, current velocity adaptation) and “biological traits” connected with life cycle and larval/adult adaptations. Species showing the highest number of advantageous traits (with only exception of Electrogena sp. cf. ujhelyii — species of taxonomically unclear status) were able to successfully survive under the unfavourable conditions of the intermittent brook. Biological traits considered more important in many respects seem to be good predictors for assessing sensitivity to extreme temperature changes, hydrological regime fluctuations and the survival/recolonisation ability of species in exposed habitats.

scholarly journals Akt Inhibition as Preconditioning Treatment to Protect Kidney Cells against Anoxia

2021 ◽  
Vol 23 (1) ◽  
pp. 152
Author(s):  
Nicolas Melis ◽  
Romain Carcy ◽  
Isabelle Rubera ◽  
Marc Cougnon ◽  
Christophe Duranton ◽  
...  
Keyword(s):  
Ischemia Reperfusion ◽  
Oxygen Demand ◽  
Ischemic Tolerance ◽  
Kidney Cells ◽  
Protective Mechanisms ◽  
Akt Phosphorylation ◽  
Mitochondrial Ros ◽  
Highly Sensitive ◽  
High Oxygen Demand ◽  
Survival Effect

Lesions issued from the ischemia/reperfusion (I/R) stress are a major challenge in human pathophysiology. Of human organs, the kidney is highly sensitive to I/R because of its high oxygen demand and poor regenerative capacity. Previous studies have shown that targeting the hypusination pathway of eIF5A through GC7 greatly improves ischemic tolerance and can be applied successfully to kidney transplants. The protection process correlates with a metabolic shift from oxidative phosphorylation to glycolysis. Because the protein kinase B Akt is involved in ischemic protective mechanisms and glucose metabolism, we looked for a link between the effects of GC7 and Akt in proximal kidney cells exposed to anoxia or the mitotoxic myxothiazol. We found that GC7 treatment resulted in impaired Akt phosphorylation at the Ser473 and Thr308 sites, so the effects of direct Akt inhibition as a preconditioning protocol on ischemic tolerance were investigated. We evidenced that Akt inhibitors provide huge protection for kidney cells against ischemia and myxothiazol. The pro-survival effect of Akt inhibitors, which is reversible, implied a decrease in mitochondrial ROS production but was not related to metabolic changes or an antioxidant defense increase. Therefore, the inhibition of Akt can be considered as a preconditioning treatment against ischemia.

scholarly journals Metabolic Signaling in a Theoretical Model of the Human Retinal Microcirculation

Photonics ◽  
2021 ◽  
Vol 8 (10) ◽  
pp. 409
Author(s):  
Julia Arciero ◽  
Brendan Fry ◽  
Amanda Albright ◽  
Grace Mattingly ◽  
Hannah Scanlon ◽  
...  
Keyword(s):  
Blood Flow ◽  
Oxygen Demand ◽  
Ocular Blood Flow ◽  
Network Location ◽  
Oxygen Levels ◽  
Wide Range ◽  
In Series ◽  
Retinal Microcirculation ◽  
Metabolic Signal ◽  
High Oxygen Demand

Impaired blood flow and oxygenation contribute to many ocular pathologies, including glaucoma. Here, a mathematical model is presented that combines an image-based heterogeneous representation of retinal arterioles with a compartmental description of capillaries and venules. The arteriolar model of the human retina is extrapolated from a previous mouse model based on confocal microscopy images. Every terminal arteriole is connected in series to compartments for capillaries and venules, yielding a hybrid model for predicting blood flow and oxygenation throughout the retinal microcirculation. A metabolic wall signal is calculated in each vessel according to blood and tissue oxygen levels. As expected, a higher average metabolic signal is generated in pathways with a lower average oxygen level. The model also predicts a wide range of metabolic signals dependent on oxygen levels and specific network location. For example, for high oxygen demand, a threefold range in metabolic signal is predicted despite nearly identical PO2 levels. This whole-network approach, including a spatially nonuniform structure, is needed to describe the metabolic status of the retina. This model provides the geometric and hemodynamic framework necessary to predict ocular blood flow regulation and will ultimately facilitate early detection and treatment of ischemic and metabolic disorders of the eye.

scholarly journals Ammonium and organic carbon co-removal under feammox-coupled-with-heterotrophy condition as an efficient approach for nitrogen treatment

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chung Phuong Le ◽  
Hai Thi Nguyen ◽  
Toi Duy Nguyen ◽  
Quyen Huynh Minh Nguyen ◽  
Hai The Pham ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Iron Reduction ◽  
Oxygen Demand ◽  
Ammonium Oxidation ◽  
Rate Limiting Step ◽  
Novel Approach ◽  
The Matrix ◽  
Nitrogen Treatment ◽  
Co Removal ◽  
High Oxygen Demand

AbstractNitrification is the rate limiting step in the nitrogen removal processes since nitrifiers have high oxygen demand, but poorly compete with aerobic heterotrophs. In a laboratory-scaled system, we investigated a process of ammonium oxidation under ferric-iron reducing condition (feammox) in the presence of organic carbon using influents with high NH4+ and COD contents, and ferrihydrite as the only electron acceptor. Batch incubations testing influents with different NH4+ and COD concentrations revealed that the [COD]/[NH4+] ratio of 1.4 and the influent redox potential ranging from − 20 to + 20 mV led to the highest removal efficiencies, i.e. 98.3% for NH4+ and 58.8% for COD. N2 was detected as the only product of NH4+ conversion, whereas NO2− and NO3− were not detected. While operating continuously with influent having a [COD]/[NH4+] ratio of 1.4, the system efficiently removed NH4+ (> 91%) and COD (> 54%) within 6 day retention time. Fluorescence in situ hybridization analyses using Cy3-labeled 16S rRNA oligonucleotide probes revealed that gamma-proteobacteria dominated in the microbial community attaching to the matrix bed of the system. The iron-reduction dependent NH4+ and COD co-removal with a thorough conversion of NH4+ to N2 demonstrated in this study would be a novel approach for nitrogen treatment.

Sign in / Sign up

Export Citation Format

Share Document