oxygen utilization
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Metabolites ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 72
Author(s):  
Avital Schurr ◽  
Salvatore Passarella

The term ‘aerobic glycolysis’ has been in use ever since Warburg conducted his research on cancer cells’ proliferation and discovered that cells use glycolysis to produce adenosine triphosphate (ATP) rather than the more efficient oxidative phosphorylation (oxphos) pathway, despite an abundance of oxygen. When measurements of glucose and oxygen utilization by activated neural tissue indicated that glucose was consumed without an accompanied oxygen consumption, the investigators who performed those measurements also termed their discovery ‘aerobic glycolysis’. Red blood cells do not contain mitochondria and, therefore, produce their energy needs via glycolysis alone. Other processes within the central nervous system (CNS) and additional organs and tissues (heart, muscle, and so on), such as ion pumps, are also known to utilize glycolysis only for the production of ATP necessary to support their function. Unfortunately, the phenomenon of ‘aerobic glycolysis’ is an enigma wherever it is encountered, thus several hypotheses have been produced in attempts to explain it; that is, whether it occurs in cancer cells, in activated neural tissue, or during postprandial or exercise metabolism. Here, it is argued that, where the phenomenon in neural tissue is concerned, the prefix ‘aerobic’ in the term ‘aerobic glycolysis’ should be removed. Data collected over the past three decades indicate that L-lactate, the end product of the glycolytic pathway, plays an essential role in brain energy metabolism, justifying the elimination of the prefix ‘aerobic’. Similar justification is probably appropriate for other tissues as well.


2021 ◽  
Vol 11 (12) ◽  
pp. 344-349
Author(s):  
D. Komolafe ◽  
M. Filippov ◽  
V. Ilyin ◽  
A. Klimenko

The results of complex studies of the quantitative relationship between the stage-by-stage mass transfer of O2 and the efficiency of cardiorespiratory system functioning in relation to its consumption in adolescents’ body under conditions of relative rest are presented. The results obtained show that in adolescents, the modes of mass transfer of O2 in the body and the nature of the respiratory and circulatory systems functioning in relation to its consumption have a number of age-related differences compared with adult men. So, in adolescents, the external respiration system at rest functions less economically than in adults. Each liter of O2 consumed by adolescents is extracted from almost 3 liters more than in adults the amount of air ventilated per minute through the lungs. The volumetric indicators of blood circulation are also higher in adolescents, which may indicate the influence of neuro-humoral rearrangements in the body during the pubertal period. The coefficient of oxygen utilization by tissues from arterial blood in adolescents turned out to be significantly higher, which may characterize a higher tension of tissue metabolic processes.


2021 ◽  
Author(s):  
Colin Berry ◽  
Andrew Morrow ◽  
Robert Sykes ◽  
Alasdair McIntosh ◽  
Anna Kamdar ◽  
...  

Abstract Background: The pathophysiology and trajectory of multiorgan involvement in post-COVID-19 syndrome is uncertain. Methods: A prospective, multicenter, longitudinal, cohort study involving post-COVID-19 patients enrolled in-hospital or early post-discharge (visit 1) and re-evaluated 28-60 days post-discharge (visit 2). Multisystem investigations included chest computed tomography with pulmonary and coronary angiography, cardiovascular and renal magnetic resonance imaging, digital electrocardiography, and multisystem biomarkers. The primary outcome was the adjudicated likelihood of myocarditis.Results: 161 patients (mean age 55 years, 43% female) and 27 controls with similar age, sex, ethnicity, and vascular risk factors were enrolled from 22 May 2020 to 2 July 2021 and had a primary outcome evaluation. Compared to controls, at 28-60 days post-discharge, patients with COVID-19 had persisting evidence of cardio-renal involvement, systemic inflammation, and hemostasis pathway activation. Myocarditis was adjudicated as being not likely (n=17; 10%), unlikely (n=56; 35%), probable (n=67; 42%) or very likely (n=21; 13%). Acute kidney injury (odds ratio, 95% confidence interval: 3.40 (1.13, 11.84); p=0.038) and low hemoglobin A1c (0.26 (0.07, 0.87); p=0.035) were multivariable associates of adjudicated myocarditis. During convalescence, compared to controls, COVID-19 was associated with worse health-related quality of life (EQ5D-5L) (p<0.001), illness perception (p<0.001), anxiety and depression (p<0.001), physical activity (p<0.001) and predicted maximal oxygen utilization (ml/kg/min) (p<0.001). These measures were associated with adjudicated myocarditis.Conclusions: The illness trajectory of COVID-19 includes persisting cardio-renal inflammation, lung damage and hemostasis activation. Adjudicated myocarditis occurred in one in eight hospitalized patients and was associated with impairments in health status, physical and psychological wellbeing during community convalescence. Public registration: ClinicalTrials.gov identifier is NCT04403607.


Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 121-121
Author(s):  
Liza Afzali-Hashemi ◽  
Lena Vaclavu ◽  
John C Wood ◽  
Aart J Nederveen ◽  
Henk J.M.M. Mutsaerts ◽  
...  

Abstract Introduction Silent cerebral infarcts (SCI) are common in patients with sickle cell disease (SCD) and thought to be caused by a mismatch between oxygen delivery and consumption. The mechanism underlying insufficient oxygen utilization is related to severity of anemia, and paradoxically, to the elevated cerebral blood flow (CBF) observed in SCD patients. CBF is elevated as a compensatory mechanism to maintain oxygen delivery, but high CBF levels can result in rapid transit of blood through the brain capillaries, limiting offloading of oxygen to the tissue; a process called arteriovenous shunting. One way to assess functional arteriovenous shunting is to use noncontrast perfusion MRI techniques in which we can assess the signal intensity of an endogenous blood tracer when it reaches the sagittal sinus. This venous signal (VS) reflects the amount of labeled blood that has not exchanged with the brain parenchyma. Under normal physiological conditions, the VS intensity will increase approximately proportionally with CBF as we expect only some of the water to exchange with tissue as it flows by. However, it is unknown whether functional shunting scales with CBF only, or whether other hemodynamic processes play a role in patients with SCD. We hypothesize that, under pathophysiological conditions such as in SCD patients, more labeled blood may pass unexchanged through the capillaries, which results in higher VS. In the present study, we investigated functional shunting by quantifying VS and assessed its association with hemodynamic, demographic and laboratory parameters in both pediatric and adult SCD patients, and controls. In addition, VS-CBF relationship was studied by further increasing CBF after a vasodilatory challenge. Methods We included 28 children (mean age 12.7 ± 2.3, 9 F) and 38 adults (mean age 32.1 ± 11.2, 14 F) with SCD (HbSS and HbS), and 10 healthy race-matched adult controls (mean age 36.4 ± 15.9, 4 F). For the CBF and VS measurements, pseudo-continuous arterial spin labelling (pCASL) data were acquired using 3T MRI. We segmented the ASL blood pool in the sagittal sinus to determine a common region of interest for each group. We used these images as masks to calculate average VS. Notably, for the comparison between children and adults the ratio between VS to gray matter CBF was used (VGR) instead of the VS, to take into account higher CBF in children. To get more insight into the oxygen utilization, oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO 2) were calculated. In adult participants acetazolamide (ACZ) was used as a vasodilatory challenge. The hematologic laboratory parameters hemoglobin (Hb) and LDH were used as markers of anemia and hemolysis, respectively. Results VS as a marker of cerebral shunting was higher in both adult and pediatric patients with SCD as compared to controls (p&lt;0.01) and increased after ACZ administration in all groups (p&lt;0.01) (Fig. 1A). VS was significantly associated with CBF both before (R 2=0.59, p&lt;0.001) and after ACZ administration (R 2=0.57, p&lt;0.001) in all groups (Fig. 1B). To test the impact of demographics and hematological parameters on the presence of shunting, VS was corrected for CBF (VS CBF) and the residuals were used in multiple linear regression analysis against age, sex, blood flow velocity in the brain feeding arteries, participant groups, hydroxyurea, Hb and LDH. Cerebral shunting, reflected by VS CBF showed significant association with Hb (Fig. 1C). In addition, we added OEF, CMRO 2 and ACZ condition as additional parameters in adults and used a linear mixed model to accommodate the repeated measures dependencies. A negative association between the level of cerebral shunting (VS CBF) and CMRO 2 was found (β=-0.79, p&lt;0.001) in all groups (Fig. 1C), and in adult patients with SCD, CMRO 2, Hb (β=-14.2 p&lt;0.001) and LDH (β=0.13, p=0.002) were significant predictors of VS CBF. Conclusion Our results show that the VS in the sagittal sinus on ASL images can be used to assess functional arteriovenous shunting in the brain. Given its negative association with CMRO 2 in combination with the negative association with hemoglobin and positive correlation with LDH, this functional shunting seems to reflect pathophysiologic shunting related to higher disease severity. Future studies will focus on the relation between functional shunting and the prevalence of SCI, investigating its link to aberrant capillary oxygen exchange in SCD. Figure 1 Figure 1. Disclosures Vaclavu: Philips Healthcare: Research Funding. Biemond: GBT: Honoraria, Research Funding, Speakers Bureau; Novo Nordisk: Honoraria; Novartis: Honoraria, Research Funding, Speakers Bureau; Celgene: Honoraria; Sanquin: Research Funding.


2021 ◽  
Vol 12 (11) ◽  
Author(s):  
Ruzhou Zhao ◽  
Xingcheng Zhao ◽  
Xiaobo Wang ◽  
Yanqi Liu ◽  
Jie Yang ◽  
...  

AbstractRapid adaptation to a hypoxic environment is an unanswered question that we are committed to exploring. At present, there is no suitable strategy to achieve rapid hypoxic adaptation. Here, we demonstrate that fasting preconditioning for 72 h reduces tissue injuries and maintains cardiac function, consequently significantly improving the survival rates of rats under extreme hypoxia, and this strategy can be used for rapid hypoxic adaptation. Mechanistically, fasting reduces blood glucose and further suppresses tissue mTOR activity. On the one hand, fasting-induced mTOR inhibition reduces unnecessary ATP consumption and increases ATP reserves under acute hypoxia as a result of decreased protein synthesis and lipogenesis; on the other hand, fasting-induced mTOR inhibition improves mitochondrial oxygen utilization efficiency to ensure ATP production under acute hypoxia, which is due to the significant decrease in ROS generation induced by enhanced mitophagy. Our findings highlight the important role of mTOR in acute hypoxic adaptation, and targeted regulation of mTOR could be a new strategy to improve acute hypoxic tolerance in the body.


2021 ◽  
Vol 20 ◽  
pp. S129
Author(s):  
B. Quertermous ◽  
N. Seigler ◽  
J. Looney ◽  
R. Crandall ◽  
M. Blackburn ◽  
...  

2021 ◽  
Vol 899 (1) ◽  
pp. 012070
Author(s):  
Liana Kemmou ◽  
Georgios Samiotis ◽  
Elisavet Amanatidou

Abstract Sustainability of activated sludge (AS) wastewater treatment processes is inexplicably linked to minimization of secondary wastes, such as waste sludge, as well as energy requirements for achieving effluent quality standards. Oxygen requirements and waste sludge management accounts for most of energy consumption in aerobic AS wastewater treatment plants (WWTPs). In this study, a novel, highly aerobic AS process, entitled complete solids retention AS process (CRAS), is being evaluated in terms of waste sludge production and biomass oxygen utilization rate. Aim of this work is to study the effect of solids retention time (SRT) on observed sludge yields and on oxygen requirements for respiration in order to evaluate CRAS process as a sustainable alternative to typical activated sludge processes.


2021 ◽  
Vol 4 (s1) ◽  
Author(s):  
Piera Mancini ◽  
Ermes Botte ◽  
Chiara Magliaro ◽  
Arti Ahluwalia

Oxygen utilization by cells has a crucial role in the design of advanced in vitro models. The aim of this study is to develop an experimental and computational pipeline for identifying oxygen metabolism parameters. We applied the approach to HepG2 cell monolayer cultures, demonstrating that such parameters depend on cell density.


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