Low Oxygen Levels Research Articles

Can Extreme Bacteria Teach Us About Extraterrestrial Life?

Have you ever wondered if there is life beyond Earth? Scientists have been studying this topic for a long time and believe the answer might lie in extremophilic microbes, small organisms that thrive in extreme environments. In a 2022 study, scientists took extremophilic microbes from an analogue environment, or place on Earth similar to Mars, and put them in simulated Martian conditions. After exposing them to higher ultraviolet radiation levels, low oxygen levels, a dry atmosphere, and moisture-free Mars-like soil, these microbes still were able to survive. This research is important in helping us understand if Mars can house life and give us clues into what that life might look like beyond Earth.

Plain language summary of the MonumenTAL-1 study of talquetamab in people with relapsed or refractory multiple myeloma.

This plain language summary describes the results of a phase 1 research study (or clinical trial) called MonumenTAL-1 published in the New England Journal of Medicine in December 2022. A phase 1 study is an early clinical trial where researchers evaluate how safe a medicine is at different doses in a small number of people. In the MonumenTAL-1 study, researchers looked at a new medicine under development called talquetamab, for people living with multiple myeloma (a type of blood cancer) who did not respond (refractory), stopped responding (relapsed), or who had difficulty dealing with their previous treatments. The phase 1 MonumenTAL-1 study was performed in 2 parts. Safety was the main focus of Part 1 in which side effects, and how serious they were, were assessed. The results of Part 1 were used to identify doses of talquetamab that were well tolerated, without a need to stop treatment or reduce the doses, for further study in Part 2. Part 2 of the study examined how well talquetamab worked to decrease signs of the cancer and what side effects, and their severity, people experienced at the doses identified in Part 1. In Part 1 of the study, researchers identified 2 doses of talquetamab for further study: 405 micrograms for every kilogram of body weight (μg/kg) given weekly and 800μg/kg every other week. All participants experienced at least one side effect of treatment at these 2 doses. Less than half of participants (43% at 405μg/kg weekly dose and 34% at the 800μg/kg every other week dose) experienced serious side effects which are those side effects that led to hospitalization, death, or permanent or life-threatening damage). The most common side effects at both doses were a condition known as cytokine release syndrome (CRS); changes in blood cell levels (where different types of cells in the blood were measured); changes in skin such as itching, dry skin, eczema, ulcers or shedding; changes in nails such as discoloration or ridging (lines or dents); and changes in sense of taste such as food tasting sour or metallic. CRS is caused by the overactivation of the immune system (the body's natural defense system) and can result in fever, feeling sick (nausea), being tired (fatigue), low blood pressure, low blood oxygen levels and body aches. Most cases of CRS, as well as most other side effects, were mild or moderate. Most common serious events were CRS, fever and bone pain. Most people had fewer signs of the cancer after taking talquetamab, and the response was similar between the 2 doses. The median duration of response at the 2 identified doses was 8-10months. Most of the side effects people experienced when taking talquetamab were mild or moderate. Most people who took talquetamab responded to the treatment even though they hadn't responded or stopped responding to previous multiple myeloma treatments or stopped taking those treatments because they were unable to tolerate them. These results demonstrate the potential of talquetamab as a treatment option in people who have used up other available therapy options. The 2 doses of talquetamab identified here are being examined in a larger group of participants to further test for safety and to test how well people respond.

Reducing racial bias in SpO2 estimation: The effects of skin pigmentation.

Accurate pulse-oximeter readings are critical for clinical decisions, especially when arterial blood-gas tests - the gold standard for determining oxygen saturation levels - are not available, such as when determining COVID-19 severity. Several studies demonstrate that pulse oxygen saturation estimated from photoplethysmography (PPG) introduces a racial bias due to the more profound scattering of light in subjects with darker skin due to the increased presence of melanin. This leads to an overestimation of blood oxygen saturation in those with darker skin that is increased for low blood oxygen levels and can result in a patient not receiving potentially life-saving supplemental oxygen. This racial bias has been comprehensively studied in conventional finger pulse oximetry but in other less commonly used measurement sites, such as in-ear pulse oximetry, it remains unexplored. Different measurement sites can have thinner epidermis compared with the finger and lower exposure to sunlight (such as is the case with the ear canal), and we hypothesise that this could reduce the bias introduced by skin tone on pulse oximetry. To this end, we compute SpO2 in different body locations, during rest and breath-holds, and compare with the index finger. The study involves a participant pool covering 6-pigmentation categories from Fitzpatrick's Skin Pigmentation scale. These preliminary results indicate that locations characterized by cartilaginous highly vascularized tissues may be less prone to the influence of melanin and pigmentation in the estimation of SpO2, paving the way for the development of non-discriminatory pulse oximetry devices.

Behavior of breast cancer cells under oxygen concentration gradients in a microfluidic device.

The tumor microenvironment (TME) is known as a chronic hypoxic environment, with spatiotemporal variation in oxygen concentration depending on the distance from blood vessels and the blood supply. In our previous studies, cancer cell behavior was observed under hypoxic conditions with spatial variation of oxygen concentration (oxygen concentration gradients); however, that under oxygen concentration gradients at low oxygen levels found in the TME has not been studied. In this study, we investigated the behavior of breast cancer cells at various oxygen concentration gradients, generated using a microfluidic device with oxygen concentration controllability. The results showed that cell distribution was altered in response to oxygen concentration, and tended to increase in a specific region at around 5% O2. Evaluation of changes in cell numbers due to proliferation, migration, and cell death indicated that proliferation strongly affected cell distribution.

Targeting Endothelial HIF2α/ARNT Expression for Ischemic Heart Disease Therapy.

Ischemic heart disease (IHD) is a major cause of mortality and morbidity worldwide, with novel therapeutic strategies urgently needed. Endothelial dysfunction is a hallmark of IHD, contributing to its development and progression. Hypoxia-inducible factors (HIFs) are transcription factors activated in response to low oxygen levels, playing crucial roles in various pathophysiological processes related to cardiovascular diseases. Among the HIF isoforms, HIF2α is predominantly expressed in cardiac vascular endothelial cells and has a key role in cardiovascular diseases. HIFβ, also known as ARNT, is the obligate binding partner of HIFα subunits and is necessary for HIFα's transcriptional activity. ARNT itself plays an essential role in the development of the cardiovascular system, regulating angiogenesis, limiting inflammatory cytokine production, and protecting against cardiomyopathy. This review provides an overview of the current understanding of HIF2α and ARNT signaling in endothelial cell function and dysfunction and their involvement in IHD pathogenesis. We highlight their roles in inflammation and maintaining the integrity of the endothelial barrier, as well as their potential as therapeutic targets for IHD.

Investigating the accuracy of blood oxygen saturation measurements in common consumer smartwatches.

Blood oxygen saturation (SpO2) is an important measurement for monitoring patients with acute and chronic conditions that are associated with low blood oxygen levels. While smartwatches may provide a new method for continuous and unobtrusive SpO2 monitoring, it is necessary to understand their accuracy and limitations to ensure that they are used in a fit-for-purpose manner. To determine whether the accuracy of and ability to take SpO2 measurements from consumer smartwatches is different by device type and/or by skin tone, our study recruited patients aged 18-85 years old, with and without chronic pulmonary disease, who were able to provide informed consent. The mean absolute error (MAE), mean directional error (MDE) and root mean squared error (RMSE) were used to evaluate the accuracy of the smartwatches as compared to a clinical grade pulse oximeter. The percent of data unobtainable due to inability of the smartwatch to record SpO2 (missingness) was used to evaluate the measurability of SpO2 from the smartwatches. Skin tones were quantified based on the Fitzpatrick (FP) scale and Individual Typology Angle (ITA), a continuous measure of skin tone. A total of 49 individuals (18 female) were enrolled and completed the study. Using a clinical-grade pulse oximeter as the reference standard, there were statistically significant differences in accuracy between devices, with Apple Watch Series 7 having measurements closest to the reference standard (MAE = 2.2%, MDE = -0.4%, RMSE = 2.9%) and the Garmin Venu 2s having measurements farthest from the reference standard (MAE = 5.8%, MDE = 5.5%, RMSE = 6.7%). There were also significant differences in measurability across devices, with the highest data presence from the Apple Watch Series 7 (88.9% of attempted measurements were successful) and the highest data missingness from the Withings ScanWatch (only 69.5% of attempted measurements were successful). The MAE, RMSE and missingness did not vary significantly across FP skin tone groups, however, there may be a relationship between FP skin tone and MDE (intercept = 0.04, beta coefficient = 0.47, p = 0.04). No statistically significant difference was found between skin tone as measured by ITA and MAE, MDE, RMSE or missingness.

Modeling ultra-high dose rate electron and proton FLASH effect with the physicochemical approach

Objective. A physicochemical model built on the radiochemical kinetic theory was recently proposed in (Labarbe et al ) to explain the FLASH effect. We performed extensive simulations to scrutinize its applicability for oxygen depletion studies and FLASH-related experiments involving both proton and electron beams. Approach. Using the dose and beam delivery parameters for each FLASH experiment, we numerically solved the radiochemical rate equations comprised of a set of coupled nonlinear ordinary differential equations to obtain the area under the curve (AUC) of radical concentrations. Main results. The modeled differences in AUC induced by ultra-high dose rates appeared to correlate well with the FLASH effect. (i) For the whole brain irradiation of mice performed in (Montay-Gruel et al ), the threshold dose rate values for memory preservation coincided with those at which AUC started to decrease much less rapidly. (ii) For the proton pencil beam scanning FLASH of (Cunningham et al ), we found linear correlations between radicals’ AUC and the biological endpoints: TGF-β1, leg contracture and plasma level of cytokine IL-6. (iii) Compatible with the findings of the proton FLASH experiment in (Kim et al ), we found that radicals’ AUC at the entrance and mid-Spread-Out Bragg peak regions were highly similar. In addition, our model also predicted ratios of oxygen depletion G-values between normal and UHDR irradiation similar to those observed in (Cao et al ) and (El Khatib et al ). Significance. Collectively, our results suggest that the normal tissue sparing conferred by UHDR irradiation may be due to the lower degree of exposure to peroxyl and superoxide radicals. We also found that the differential effect of dose rate on the radicals’ AUC was less pronounced at lower initial oxygen levels, a trait that appears to align with the FLASH differential effect on normal versus tumor tissues.

STAT3 and HIF1α cooperatively mediate the transcriptional and physiological responses to hypoxia

STAT3 and HIF1α are two fundamental transcription factors involved in many merging processes, like angiogenesis, metabolism, and cell differentiation. Notably, under pathological conditions, the two factors have been shown to interact genetically, but both the molecular mechanisms underlying such interactions and their relevance under physiological conditions remain unclear. In mouse embryonic stem cells (ESCs) we manage to determine the specific subset of hypoxia-induced genes that need STAT3 to be properly transcribed and, among them, fundamental genes like Vegfa, Hk1, Hk2, Pfkp and Hilpda are worth mentioning. Unexpectedly, we also demonstrated that the absence of STAT3 does not affect the expression of Hif1α mRNA nor the stabilization of HIF1α protein, but the STAT3-driven regulation of the hypoxia-dependent subset of gene could rely on the physical interaction between STAT3 and HIF1α. To further elucidate the physiological roles of this STAT3 non-canonical nuclear activity, we used a CRISPR/Cas9 zebrafish stat3 knock-out line. Notably, hypoxia-related fluorescence of the hypoxia zebrafish reporter line (HRE:mCherry) cannot be induced when Stat3 is not active and, while Stat3 Y705 phosphorylation seems to have a pivotal role in this process, S727 does not affect the Stat3-dependent hypoxia response. Hypoxia is fundamental for vascularization, angiogenesis and immune cells mobilization; all processes that, surprisingly, cannot be induced by low oxygen levels when Stat3 is genetically ablated. All in all, here we report the specific STAT3/HIF1α-dependent subset of genes in vitro and, for the first time with an in vivo model, we determined some of the physiological roles of STAT3-hypoxia crosstalk.

The influence of negative pressure wound therapy on bacterial and fungal growth

BackgroundThe use of negative pressure wound therapy (NPWT) in superinfected wounds is controversial. The mechanism of action is unclear, but recent studies have shown lower atmospheric oxygen levels within the dressing. Therefore, different oxygen-favoring bacteria and fungi might benefit or face impaired thriving conditions. The aim of this in vitro study is to investigate the influence of NPWT on bacterial and fungal growth. MethodsSalmonella enterica subsp. enterica serovar Typhimurium, Pseudomonas aeruginosa and Candida albicans strains were cultured on concentrated agars and attached to a standard NPWT-device. After 48 hours, colonies were separately harvested from the agar and foam. Optical density (OD) was obtained in order to estimate bacterial loads. ResultsFor all tested microorganisms, no overall significant differences were found compared to controls. Subanalysis showed lower OD levels from the agar beneath the foam in the NPWT-group. ConclusionNPWT removed bacteria and fungi from the wound surface but accumulation is found within the foam. The use of NPWT showed no influence on bacterial or fungal growth selection. With superinfected wounds, the use of NPWT should thoroughly be evaluated as toxins and virulence factors may not fully be evacuated.

Role of endothelial cells and angiotensin converting enzyme-II in COVID-19 and brain damages post-infection.

Severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) causes coronavirus disease 2019 (COVID-19), which became a pandemic in late 2019 and early 2020. Apart from many other symptoms of this infection, such as loss of smell and taste, rashes, body aches, fatigue, and psychological and cardiac symptoms, it also causes vasodilation in response to inflammation via nitric oxide release. SARS CoV-2 affects microcirculation, resulting in the swelling and damage of endothelial cells, micro thrombosis, constriction of capillaries, and damage to pericytes that are vital for the integrity of capillaries, angiogenesis, and the healing process. Cytokine storming has been associated with COVID-19 illness. Capillary damage and congestion may cause limited diffusion exchange of oxygen in the lungs and hence hypoxemia and tissue hypoxia occur. This perspective study will explore the involvement of capillary damage and inflammation by their interference with blood and tissue oxygenation as well as brain function in the persistent symptoms and severity of COVID-19. The overall effects of capillary damage due to COVID-19, microvascular damage, and hypoxia in vital organs are also discussed in this perspective. Once initiated, this vicious cycle causes inflammation due to hypoxia, resulting in limited capillary function, which in turn causes inflammation and tissue damage. Low oxygen levels and high cytokines in brain tissue may lead to brain damage. The after-effects may be in the form of psychological symptoms such as mood changes, anxiety, depression, and many others that need to be investigated.

Inoculation with extreme endophytes improves performance and nutritional quality in crop species grown under exoplanetary conditions.

Technological advances have made possible long space travels and even exoplanetary colonies in the future. Nevertheless, the success of these activities depends on our ability to produce edible plants in stressful conditions such as high radiation, extreme temperatures and low oxygen levels. Since beneficial microorganisms, such as fungal endophytes from extreme environments, have helped agriculture cope with those difficulties, endophytic fungi may be a putative tool to ensure plant growth under exoplanetary conditions. Additionally, growing crops in polyculture has been shown to increase productivity and spatial efficiency, which is essential given the likely space restrictions in such conditions. We evaluated the effect of the inoculation with a mix of two fungal endophytes from the Atacama Desert on performance (survival and biomass) and nutritional quality of three crop species (lettuce, chard and spinach) grown under exoplanetary conditions. In addition, we measured the amount of antioxidants (flavonoids and phenolics) as possible mechanisms to cope with such abiotic conditions. The exoplanetary conditions were; high UV radiation, low temperature, low water availability, and low oxygen levels. These crops were put in growing chambers in monoculture, dual culture and polyculture (the three species in the same pot) for 30 days. Our results show that inoculation with extreme endophytes improved survival by ca. 15 - 35% and biomass by ca. 30 - 35% in all crop species. The most evident increase was when grown in polyculture, except for survival in spinach, where inoculated plants had higher survival only in dual culture. Nutritional quality and the amount of the antioxidant compounds antioxidants increased in all crop species when inoculated with the endophytes. Overall, fungal endophytes isolated from extreme environments such as the Atacama Desert, the driest desert in the world, could be a key biotechnological tool for future space agriculture, helping plants cope with environmental stress. Additionally, inoculated plants should be grown in polyculture to increase crop turnover and space-use efficiency. Lastly, these results provide useful insights to face the future challenges of space-farming.

Oxygen and mechanical stretch in the developing lung: risk factors for neonatal and pediatric lung disease.

Chronic airway diseases, such as wheezing and asthma, remain significant sources of morbidity and mortality in the pediatric population. This is especially true for preterm infants who are impacted both by immature pulmonary development as well as disproportionate exposure to perinatal insults that may increase the risk of developing airway disease. Chronic pediatric airway disease is characterized by alterations in airway structure (remodeling) and function (increased airway hyperresponsiveness), similar to adult asthma. One of the most common perinatal risk factors for development of airway disease is respiratory support in the form of supplemental oxygen, mechanical ventilation, and/or CPAP. While clinical practice currently seeks to minimize oxygen exposure to decrease the risk of bronchopulmonary dysplasia (BPD), there is mounting evidence that lower levels of oxygen may carry risk for development of chronic airway, rather than alveolar disease. In addition, stretch exposure due to mechanical ventilation or CPAP may also play a role in development of chronic airway disease. Here, we summarize the current knowledge of the impact of perinatal oxygen and mechanical respiratory support on the development of chronic pediatric lung disease, with particular focus on pediatric airway disease. We further highlight mechanisms that could be explored as potential targets for novel therapies in the pediatric population.

Life Threatening Hypoxemia Associated with COVID-19 (Review)

COVID-19, which has become a pandemic is caused by coronavirus and led to severe acute respiratory syndrome. Its complication include respiratory incompetence, damage in the muscles of the lung and heart , problems in nervous system and kidney or death. One of the characteristic symptoms of COVID-19 is the low levels of oxygen in patients' blood, a condition known as hypoxemia. Patients with hypoxemia often show the following symptoms: coughing wheezing, difficulty in breathing, headache, feeling disoriented, cyanosis in which the skin, lips, or fingernails become blue colored, even though hypoxemia is diagnosed by some tests, such as analysis of blood gas and pulse oximetry, caution should be considered when pulse oximetry interpreted, because of shifting in the left-sided of the oxyhemoglobin dissociation curve. Hypoxemia causes acute respiratory distress syndrome, that includes inflammation and edema, leadings to impairment in the alveolar homeostasis, modification in the physiology of lung resulting in vascular thrombosis, endothelial inflammation and pulmonary fibrosis, therefore any tardiness in diagnosis and introducing proper treatment can led to mortal outcomes. In this review we present hypoxemia as one of the symptoms resulting from infection with COVID-19 infection, focusing on their types, causes and possible treatment for this condition.

Elevated cfDNA after exercise is derived primarily from mature polymorphonuclear neutrophils, with a minor contribution of cardiomyocytes

Strenuous physical exercise causes a massive elevation in the concentration of circulating cell-free DNA (cfDNA), which correlates with effort intensity and duration. The cellular sources and physiological drivers of this phenomenon are unknown. Using methylation patterns of cfDNA and associated histones, we show that cfDNA in exercise originates mostly in extramedullary polymorphonuclear neutrophils. Strikingly, cardiomyocyte cfDNA concentration increases after a marathon, consistent with elevated troponin levels and indicating low-level, delayed cardiac cell death. Physical impact, low oxygen levels, and elevated core body temperature contribute to neutrophil cfDNA release, while muscle contraction, increased heart rate, β-adrenergic signaling, or steroid treatment fail to cause elevation of cfDNA. Physical training reduces neutrophil cfDNA release after a standard exercise, revealing an inverse relationship between exercise-induced cfDNA release and training level. We speculate that the release of cfDNA from neutrophils in exercise relates to the activation of neutrophils in the context of exercise-induced muscle damage.

Role of MicroRNAs in Regulation of Cellular Response to Hypoxia.

Hypoxia causes changes in transcription of the genes that contribute to adaptation of the cells to low levels of oxygen. The main mechanism regulating cellular response to hypoxia is activation of hypoxia-inducible transcription factors (HIF), which include several isoforms and control expression of more than a thousand genes. HIF activity is regulated at various levels, including by small non-coding RNA molecules called microRNAs (miRNAs). miRNAs regulate cellular response to hypoxia by influencing activation of HIF, its degradation, and translation of HIF-dependent proteins. At the same time, HIFs also affect miRNAs biogenesis. Data on the relationship of a particular HIF isoform with miRNAs are contradictory, since studies have been performed using different cell lines, various types of experimental animals and clinical material, as well as at different oxygen concentrations and durations of hypoxic exposure. In addition, HIF expression may be affected by the initial resistance of organisms to lack of oxygen, which has not been taken into account in the studies. This review analyzes the data on the effect of hypoxia on biogenesis and functioning of miRNAs, as well as on the effect of miRNAs on mRNAs of the genes involved in adaptation to oxygen deficiency. Understanding the mechanisms of relationship between HIF, hypoxia, and miRNA is necessary to develop new approaches to personalized therapy for diseases accompanied by oxygen deficiency.

Advanced Wireless Multipurpose Mine Detection Robot

Abstract: The tasks involved in rescue operations in coal mines are hazardous and life-threatening. Many explosions take place from time to time, but the miners are not aware of them. It is also very difficult for the rescue squad to comprehend the situation within the mine. Hazardous gases, high temperatures, methane leaks, and low oxygen levels are examples of environmental issues. An environmental monitoring robot system for remote sensing in coal mines is introduced in this study. This robot system is designed to remotely collect information about the coal mine's surroundings, in addition to performing observational tasks. As a result, this device can be thought of as a multifunctional sensor that enables distant sensing. When it senses danger, the robot system will send out signals warning rescuers to keep their distance. Lessons from the creation of the robot system may be applied to the development of future search-and-rescue systems

Impacts of seasonal variations of the Tropical Pacific ocean temperatures on upper ocean oxygen response

The El Niño–Southern Oscillation (ENSO) is the most dominant natural variability in the Earth system, which represents seasonal-to-interannual variations of the surface equatorial Pacific Ocean temperatures and subsurface ocean interior. Impacting the physical upper ocean characteristics, ENSO exerts significant influences on the marine ecosystem, such as oxygen and phytoplankton concentrations via strong quasiperiodic oscillation between El Niño (warm phase) and La Niña (cold phase) events. The present study uses observational reanalysis and satellite data to investigate seasonal variations of ENSO and their impacts on marine biogeochemical processes. The results show that the oxygen and chlorophyll anomalies in the upper ocean exhibit different seasonal responses to ENSO. While both the summer and winter season biological responses significantly lag ENSO, the concentration of oxygen and phytoplankton during summer (winter) has no (large) concurrent covariability with ENSO. Given a strong negative correlation between chlorophyll-based indices and El Niño events, increasing mean ocean temperatures and ocean extreme events may induce lower upper-ocean oxygen levels, leading to possible risks in the ecosystem over the tropical Pacific Ocean.

0456 Association of MOCA scores in individuals with Mild Cognitive Impairment-Alzheimer Disease and Obstructive Sleep Apnea

Abstract Introduction Mild cognitive impairment (MCI) is considered a transitional stage between normal aging and dementia. Studies have demonstrated an association with rate of progression of MCI and dementia in individuals with OSA compared to those without OSA. The varying degree of hypoxia, sleep fragmentation and poor quality of sleep in OSA patients has been associated with increased risk of stroke, memory impairment, cardiac arrhythmias, dyslipidemia, hypertension, obesity and glucose intolerance. Identifying different variables in sleep study that can be linked with MCI and AD is helpful. We compared patients' MOCA score at the time of sleep study and compared it with multiple macro and micro variables tested on the sleep study. Methods Data was presented as mean ± (SD) or median [25th, 75th percentiles] for continuous variables and N (%) for categorical variables. Comparisons were performed between baseline MOCA groups (0-17 vs. 18-30) using two-sample T-test or Wilcoxon rank sum test for continuous variables based on distribution, and chi-square test or Fisher’s exact test for categorical variables. Linear regression was used to assess the relationship between baseline MOCA and sleep measures before and after adjustment for covariates. Covariates included age, gender, race, and BMI. Results Patients with smaller MOCA score were older (71.4 ± 8.7 vs. 68.1 ± 9.4, p=0.002), predominantly black (17.8% vs. 10.8%, p=0.013), weigh lower (median [IQR]: 80.5 [69.2, 94.0] vs. 86.2 [74.0, 99.0], p=0.023) and had less prevalence in ADHD, anxiety, depression, GERD and headache (p=0.034,0.024,0.013,0.016,0.040, respectively). After covariates adjustment (age, sex, race and BMI), when percent sleep time with SaO2< 90% increase 10%, MOCA would decrease 0.24 (coefficient -0.21, 95%CI [-0.41,-0.01], p=0.043); when SaO2 nadir increased 10%, MOCA would increase 0.68 (coefficient 0.68, 95%CI [0.05,1.32], p=0.035); when sleep stage %N1 increased 1%, MOCA would decrease 0.04 (coefficient -0.04, 95%CI [-0.08,-0.01], p=0.011). Conclusion Changes in oxygen levels during sleep showed direct correlation between MOCA score in individuals with MCI and AD, at the time of sleep study. Decline in MOCA scores were directly associated with degree of hypoxia observed during the sleep studies. The study showed association of worsening MCI and AD with lower oxygen levels in patients with OSA. Support (if any)

Investigating the Relationship Between High Levels of Angiotensin II in Plasma and the Rate of Deterioration in Hypertensive Patients to COVID-19

Introduction: The COVID-19 crisis poses a heightened risk to vulnerable populations. Considering factors influencing deterioration, complications, and mortality, it is especially important to pay attention to these groups, including persons with hypertension (HTN) and diabetes. This study aimed to investigate the correlation between the angiotensin II (ANG II) level and the disease severity and clinical course in COVID-19 patients. Methods: A cross-sectional study was conducted on 50 COVID-19 patients (mean age 59.1±20) admitted to Sinai hospital in Hamedan. The blood samples of the patients were taken during hospitalization and discharge, and the plasma ANG II level was measured using an enzyme-linked immunosorbent assay kit. The quantitative comparison was analyzed with paired t test and qualitative comparison with the chi-square test. The correlation of variables was checked with the Pearson test, and P<0.05 was considered statistically significant. Results: Overall, 44%, 16%, and 10% of COVID-19 patients had HTN, cardiovascular disease (CVD), and 10% diabetes, respectively. The oxygen level of 82% of the patients was below 90, of which 68% were intubated, and the lowest oxygen levels were observed in patients with HTN and CVD with 2 deaths. The primary and secondary examination of the ANG II level demonstrated that its level was significantly higher during illness compared to full recovery and decreased during recovery. Conclusion: The ANG II level is related to the severity of the disease in the early stages of 2019- nCoV infection. Therefore, HTN or other diseases that affect the level of ANG II in the blood can increase the severity of the disease.

Hemoglobin, maximal heart rate and work capacity, as well as time to exhaustion are significantly improved with combined hypoxia and aerobic exercise training in healthy adults: a meta-analysis

Abstract Funding Acknowledgements Type of funding sources: None. Background/Introduction Hypoxic conditions have been used for a variety of reasons and have been implemented in multiple ways in an attempt to improve physiologic performance. Hypoxic conditions are administered via real or simulated altitude or by breathing lower levels of oxygen via facemask to improve different physiologic processes. Maximal work capacity (MWC) and time to exhaustion (TTE) are important factors related to sports performance. It is unclear how aerobic exercise (AE) with hypoxia effects MWC, TTE, and maximal heart rate (MHR) as well as hemoglobin (Hgb) and hematocrit (Hct) concentrations. Purpose Examine the effects of chronic AE with and without hypoxia on MWC, TTE, MHR, Hgb, and Hct. Methods A comprehensive search using PubMed, Cochrane, and PEDro was performed using a variety of keyword permutations on "hypoxia" and "aerobic exercise" in healthy adults. Inclusion criteria were studies with both a control and experimental group in which chronic AE was performed with and without hypoxia and MWC and TTE were provided in Watts and seconds, respectively. Study quality was assessed using the PEDro scale. Statistical analyses were performed using R with sub-analyses examining changes in Hgb, Hct, and MHR. Results A total of 16 studies met the inclusion criteria yielding a total sample size of 389 healthy adults. Study quality ranged from 4 to 6 out of 10 (mode=5). Significant tests for the overall effect of AE with hypoxia compared to AE without hypoxia on MWC and TTE were found under random-effects models (Z=2.83, p<.001, 95% C.I. = 0.29-1.60 and Z=2.94, p<.001, 95% C.I. = 0.80-4.00, respectively). A significant test for the overall effect of AE with hypoxia compared to AE without hypoxia on Hgb was also found (Z=2.06, p=.03, 95% C.I. = 0.01-0.60; fixed-effects model), but a non-significant overall effect on Hct was observed (Z=1.24, p=.21, 95% C.I. = -0.19-0.85; random-effects model). A significant test for the overall effect of AE with hypoxia compared to AE without hypoxia on MHR was also found (Z=2.84, p<.001, 95% C.I. = 0.19-1.04). Substantial heterogeneity was observed in all analyses (I2 range of 64% - 89%). Conclusions Chronic AE with hypoxia elicits a significantly greater increase in MWC and TTE compared to AE without hypoxia in healthy adults. The significant improvement in Hgb and increased MHR provides a rationale for the improvement in MWC and TTE associated with chronic AE combined with hypoxia. Improvements in MWC and TTE have the capacity to improve sport performance. Further investigation of AE with and without hypoxia on specific sports and on other physiologic measures is warranted.