Adaptations to High-Altitude Hypoxia

2021 ◽  
Author(s):  
Cynthia M. Beall ◽  
Kingman P. Strohl
Keyword(s):  
High Altitude ◽  
Oxygen Delivery ◽  
Hemoglobin Concentration ◽  
Barometric Pressure ◽  
Ambient Air ◽  
Extreme Environment ◽  
Indigenous Populations ◽  
East African ◽  
Short Term

Biological anthropologists aim to explain the hows and whys of human biological variation using the concepts of evolution and adaptation. High-altitude environments provide informative natural laboratories with the unique stress of hypobaric hypoxia, which is less than usual oxygen in the ambient air arising from lower barometric pressure. Indigenous populations have adapted biologically to their extreme environment with acclimatization, developmental adaptation, and genetic adaptation. People have used the East African and Tibetan Plateaus above 3,000 m for at least 30,000 years and the Andean Plateau for at least 12,000 years. Ancient DNA shows evidence that the ancestors of modern highlanders have used all three high-altitude areas for at least 3,000 years. It is necessary to examine the differences in biological processes involved in oxygen exchange, transport, and use among these populations. Such an approach compares oxygen delivery traits reported for East African Amhara, Tibetans, and Andean highlanders with one another and with short-term visitors and long-term upward migrants in the early or later stages of acclimatization to hypoxia. Tibetan and Andean highlanders provide most of the data and differ quantitatively in biological characteristics. The best supported difference is the unelevated hemoglobin concentration of Tibetans and Amhara compared with Andean highlanders as well as short- and long-term upward migrants. Moreover, among Tibetans, several features of oxygen transfer and oxygen delivery resemble those of short-term acclimatization, while several features of Andean highlanders resemble the long-term responses. Genes and molecules of the oxygen homeostasis pathways contribute to some of the differences.

scholarly journals Physiology and Medicine at High Altitude: The Exposure and the Stress

2018 ◽  
Vol 3 (3) ◽  
pp. 203 ◽  
Author(s):  
Anil Gurtoo
Keyword(s):  
High Altitude ◽  
Acute Mountain Sickness ◽  
Hemoglobin Concentration ◽  
Barometric Pressure ◽  
Extreme Environment ◽  
Incidence Rates ◽  
Oxygen Requirement ◽  
Classic Model ◽  
Mountain Sickness ◽  
High Altitude Illness

<p>Increase in altitude causes decrease in atmospheric barometric pressure that results in decrease of inspired<br />partial pressure of oxygen, a source for stress and pose a challenge to climbers/trekkers or persons posted on<br />high altitude areas. This review discusses about the high altitude sickness, their incidence rates, pathophysiology<br />and the classic model of acclimatisation, which explains about how oxygen requirement in extreme environment<br />is achieved by complex interplay among pulmonary, hematological and cardiovascular processes. The acute<br />high altitude illness (AHAI) is basically composed of two syndromes: cerebral and pulmonary that can afflict<br />un-acclimatised climbers/trekkers. The cerebral syndrome includes acute mountain sickness (AMS) and high<br />altitude cerebral oedema (HACO) and pulmonary syndrome typically refers to high altitude pulmonary oedema<br />(HAPO). The core physiological purpose, according to the classic model is centered upon the optimisation of<br />increased delivery of oxygen to the cells through a coherent response involving increased ventilation, cardiac<br />output and hemoglobin concentration with aim to increase the oxygen flux across the oxygen cascade, which<br />will help in preventing the development of majority of high altitude illness.</p>

scholarly journals Acute and chronic exposure to air pollution in relation with incidence, prevalence, severity and mortality of COVID-19: a rapid systematic review

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Patrick D. M. C. Katoto ◽  
Amanda S. Brand ◽  
Buket Bakan ◽  
Paul Musa Obadia ◽  
Carsi Kuhangana ◽  
...  
Keyword(s):  
Air Pollution ◽  
Chronic Exposure ◽  
Ambient Air ◽  
Short Term ◽  
Incidence And Mortality ◽  
Acute And Chronic Exposure ◽  
Anthropogenic Pollutant ◽  
Incident Cases ◽  
Incidence Prevalence

Abstract Background Air pollution is one of the world’s leading mortality risk factors contributing to seven million deaths annually. COVID-19 pandemic has claimed about one million deaths in less than a year. However, it is unclear whether exposure to acute and chronic air pollution influences the COVID-19 epidemiologic curve. Methods We searched for relevant studies listed in six electronic databases between December 2019 and September 2020. We applied no language or publication status limits. Studies presented as original articles, studies that assessed risk, incidence, prevalence, or lethality of COVID-19 in relation with exposure to either short-term or long-term exposure to ambient air pollution were included. All patients regardless of age, sex and location diagnosed as having COVID-19 of any severity were taken into consideration. We synthesised results using harvest plots based on effect direction. Results Included studies were cross-sectional (n = 10), retrospective cohorts (n = 9), ecological (n = 6 of which two were time-series) and hypothesis (n = 1). Of these studies, 52 and 48% assessed the effect of short-term and long-term pollutant exposure, respectively and one evaluated both. Pollutants mostly studied were PM2.5 (64%), NO2 (50%), PM10 (43%) and O3 (29%) for acute effects and PM2.5 (85%), NO2 (39%) and O3 (23%) then PM10 (15%) for chronic effects. Most assessed COVID-19 outcomes were incidence and mortality rate. Acutely, pollutants independently associated with COVID-19 incidence and mortality were first PM2.5 then PM10, NO2 and O3 (only for incident cases). Chronically, similar relationships were found for PM2.5 and NO2. High overall risk of bias judgments (86 and 39% in short-term and long-term exposure studies, respectively) was predominantly due to a failure to adjust aggregated data for important confounders, and to a lesser extent because of a lack of comparative analysis. Conclusion The body of evidence indicates that both acute and chronic exposure to air pollution can affect COVID-19 epidemiology. The evidence is unclear for acute exposure due to a higher level of bias in existing studies as compared to moderate evidence with chronic exposure. Public health interventions that help minimize anthropogenic pollutant source and socio-economic injustice/disparities may reduce the planetary threat posed by both COVID-19 and air pollution pandemics.

Oxygen transport to exercising leg in chronic hypoxia

1988 ◽  
Vol 65 (6) ◽  
pp. 2592-2597 ◽  
Author(s):  
P. R. Bender ◽  
B. M. Groves ◽  
R. E. McCullough ◽  
R. G. McCullough ◽  
S. Y. Huang ◽  
...  
Keyword(s):  
Blood Flow ◽  
Sea Level ◽  
Chronic Hypoxia ◽  
Peripheral Resistance ◽  
Hemoglobin Concentration ◽  
Barometric Pressure ◽  
Ambient Air ◽  
Leg Blood Flow ◽  
State Cycle ◽  
O2 Delivery

Residence at high altitude could be accompanied by adaptations that alter the mechanisms of O2 delivery to exercising muscle. Seven sea level resident males, aged 22 +/- 1 yr, performed moderate to near-maximal steady-state cycle exercise at sea level in normoxia [inspired PO2 (PIO2) 150 Torr] and acute hypobaric hypoxia (barometric pressure, 445 Torr; PIO2, 83 Torr), and after 18 days' residence on Pikes Peak (4,300 m) while breathing ambient air (PIO2, 86 Torr) and air similar to that at sea level (35% O2, PIO2, 144 Torr). In both hypoxia and normoxia, after acclimatization the femoral arterial-iliac venous O2 content difference, hemoglobin concentration, and arterial O2 content, were higher than before acclimatization, but the venous PO2 (PVO2) was unchanged. Thermodilution leg blood flow was lower but calculated arterial O2 delivery and leg VO2 similar in hypoxia after vs. before acclimatization. Mean arterial pressure (MAP) and total peripheral resistance in hypoxia were greater after, than before, acclimatization. We concluded that acclimatization did not increase O2 delivery but rather maintained delivery via increased arterial oxygenation and decreased leg blood flow. The maintenance of PVO2 and the higher MAP after acclimatization suggested matching of O2 delivery to tissue O2 demands, with vasoconstriction possibly contributing to the decreased flow.

Effects of adrenocorticotropin on temperature- and pressure-dependent metabolic functions

1959 ◽  
Vol 197 (6) ◽  
pp. 1291-1296 ◽  
Author(s):  
Henry B. Hale ◽  
Roy B. Mefferd
Keyword(s):  
Barometric Pressure ◽  
Male Rats ◽  
Short Term ◽  
Metabolic Functions ◽  
Metabolic States ◽  
Environmental Extremes ◽  
Temperature And Pressure ◽  
Hot Environments ◽  
Low Dosage

Effects of adrenocorticotropin (ACTH) in low dosage on metabolic aspects were determined in adult male rats acclimated to cold, neutral or hot environments or to low barometric pressure. Urinary determinations provided the means for indirectly assessing metabolic states. The metabolic aspects studied were Na, K, Ca, P, Mg, urea, uric acid, creatinine, creatine, taurine, ß-alanine, glycine, α-alanine, valine, methionine, serine, threonine, tyrosine, glutamic acid, aspartic acid, lysine, arginine, histidine, glucose, glucuronic acid, phenolic acids and coproporphyrin. Additionally, fecal determinations were made for coproporphyrin, protoporphyrin and deuteroporphyrin. The interplay between endocrine and environmental factors and their importance to metabolic states during short-term and long-term exposures to environmental extremes thus received some clarification. With the low dosage employed, ACTH had a ‘restraining’ influence on nonspecific metabolic responses.

scholarly journals Collaboration and discord in international debates about coca chewing, 1949–1950

2018 ◽  
Vol 5 (2) ◽  
Author(s):  
Adam Warren
Keyword(s):  
United Nations ◽  
High Altitude ◽  
Health Effects ◽  
Indigenous Peoples ◽  
Field Survey ◽  
Indigenous Populations ◽  
National Politics ◽  
Internal Colonialism ◽  
Global North

This essay complicates our thinking about unequal North-South ‘collaborations’ by considering how distinct scientific traditions, national politics, forms of racial thinking, and conditions of internal colonialism in the global South shape relations with individuals and entities based in the global North. It does this by examining conflicts between Peruvian scientists and the United Nations’ Commission for the Study of the Coca Leaf, which visited Peru and Bolivia in 1949 to investigate the health effects of coca consumption on highland Indigenous populations. Sent at the Peruvian government’s invitation, commission members saw themselves as conducting a field survey. However, they quickly found themselves embroiled in conflict with a Peruvian high-altitude physiologist, Carlos Monge, who sought long-term, laboratory-based collaboration. Monge’s scholarship and experiments proved controversial for UN authorities because they emphasized the racial alterity of highland Indigenous peoples even as he and his peers disagreed about the health effects of coca chewing.

scholarly journals Experimental investigations of wooden and concrete composite beams subject to long-term load

2018 ◽  
Vol 174 ◽  
pp. 01016 ◽  
Author(s):  
Mariusz Czabak ◽  
Zbigniew Perkowski
Keyword(s):  
Ambient Air ◽  
Composite Beams ◽  
Qualitative Assessment ◽  
Experimental Investigations ◽  
Extended Version ◽  
Short Term ◽  
Static Loads ◽  
Total Load ◽  
Creep Temperature

The issue of reinforcing wooden beams via their joining with a concrete upper slab is still being widely discussed in the literature of the problem. The paper is an extended version of the authors' previous research conducted in this subject matter for short-term static loads. The current work takes into account also a qualitative assessment of two-year behaviour of the structure based on the measurements of its creep, temperature and relative humidity of the ambient air in typical in-door conditions. The beams were 4-m long and subject to a total load of 10 kN. Their layers had crosssectional dimensions equal to 95 mm x 195 mm and 300 mm x 50 mm for the wooden rib and reinforced concrete upper slab, respectively.

P–736 Elevated levels of ambient air pollutants increase the primary sex ratio in human embryos

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
M Maluf ◽  
M Malu. Perin ◽  
P O Malu. Perin ◽  
P Perin
Keyword(s):  
Air Pollution ◽  
Sex Ratio ◽  
Air Pollutants ◽  
Ambient Air ◽  
Outdoor Air ◽  
Exposure Risk ◽  
Short Term ◽  
Primary Sex Ratio ◽  
Short Term Exposure

Abstract Study question Are there any associations between ambient outdoor air pollution and the primary sex ratio (PSR)? Summary answer Short-term exposure to increased PM10, PM2.5 and NO2 levels were significantly associated with higher PSR. What is known already PSR estimates represent a backward extrapolation from data based on spontaneous or induced abortions, fetal deaths or live births and are usually male-biased. A recent study, analyzing 3- to 6-day-old embryos derived from assisted reproductive technology (ART) procedures, showed that the sex ratio at conception is unbiased (0.5). Epidemiologic studies of air pollution on secondary (birth) sex ratio showed that higher levels of particulate pollution were associated with increased rates of female birth. However, a direct association between urban levels of air pollutants and PSR has not been reported. Study design, size, duration A retrospective cohort study was carried out to assess the impact of long- or short-term exposure to six ambient outdoor air pollutants (particulate matter, PM10µm and PM2.5µm; SO2; CO; NO2; O3) on PSR (XY/XX) of couples undergoing their first IVF cycle for preimplantation genetic screening (N = 337). Data was from fixed air quality monitoring stations across the city between January 2014 and December 2018. Embryos with sex chromosome abnormalities were excluded from the analysis. Participants/materials, setting, methods Average concentrations of the pollutants for the 90 (long-term exposure) and 15 days (short-term exposure) predating oocyte retrieval represented the exposures of interest. Pollutant levels were categorized into quartiles (Q1 to Q4) and exposure risk was divided into two periods in which average concentrations and confidence intervals for the pollutants were in the upper quartile (Q4 period) or not (Q1-Q3 period). The strength association between exposure risk and PSR was performed through analysis of covariance. Main results and the role of chance The estimated means of PM10, PM2.5, SO2, NO2, O3 and CO for Q1-Q3/Q4 periods were 27.7/39.3, 16.7/23.7, 2.5/3.9, 37.0/46.4, 32.2/45.3 µg/m3 and 0.64/0.87 ppm and 26.3/43.0, 16.0/26.3, 2.4/4.2, 36.5/47.8, 31.7/50.4 µg/m3 and 0.62/0.90 ppm for long- and short-term exposures, respectively. PM10, PM2.5 and NO2 levels in the Q4 period had significantly higher PSR (138.1, 134.0 and 137.6) when compared to Q1-Q3 period (94.4, 98.1 and 96.4) for the short-term exposure (p = 0.0193; p = 0.0439; p = 0.0180, respectively). PM10, PM2.5, SO2, NO2 and CO levels in the Q4 and Q1-Q3 periods for the long-term exposure showed no significant effect on PSR. Contrastingly, O3 levels in the Q4 period had significantly lower PSR (82.6) when compared to Q1-Q3 (115.9) for the long-term exposure (p = 0.0202). A monotonic increase in PSR was observed with increased PM10 concentration in the Q4 period for the short-term exposure (F-ratio: 4.4476; p = 0.0352). Limitations, reasons for caution Some limitations of the study should be underlined, such as its retrospective nature, exposure assessment based on pollutant levels derived from a network average across city sites, and limited extrapolation of the results to the general population. Wider implications of the findings: Our data suggest that short-term exposure to environmental factors could affect the primary sex ratio in polluted seasons or cities. A monotonic effect on PSR in the case of exposure to increasing PM10 levels was identified. Trial registration number Not applicable

scholarly journals Comparison of nitrous oxide (N<sub>2</sub>O) analyzers for high-precision measurements of atmospheric mole fractions

2016 ◽  
Vol 9 (3) ◽  
pp. 1221-1238 ◽  
Author(s):  
Benjamin Lebegue ◽  
Martina Schmidt ◽  
Michel Ramonet ◽  
Benoit Wastine ◽  
Camille Yver Kwok ◽  
...  
Keyword(s):  
Water Vapor ◽  
High Precision ◽  
Temperature Stability ◽  
Ambient Air ◽  
Observation System ◽  
Monitoring Networks ◽  
Atmospheric Measurements ◽  
Short Term ◽  
Highly Nonlinear

Abstract. Over the last few decades, in situ measurements of atmospheric N2O mole fractions have been performed using gas chromatographs (GCs) equipped with electron capture detectors. This technique, however, becomes very challenging when trying to detect the small variations of N2O as the detectors are highly nonlinear and the GCs at remote stations require a considerable amount of maintenance by qualified technicians to maintain good short-term and long-term repeatability. With new robust optical spectrometers now available for N2O measurements, we aim to identify a robust and stable analyzer that can be integrated into atmospheric monitoring networks, such as the Integrated Carbon Observation System (ICOS). In this study, we present the most complete comparison of N2O analyzers, with seven analyzers that were developed and commercialized by five different companies. Each instrument was characterized during a time period of approximately 8 weeks. The test protocols included the characterization of the short-term and long-term repeatability, drift, temperature dependence, linearity and sensitivity to water vapor. During the test period, ambient air measurements were compared under field conditions at the Gif-sur-Yvette station. All of the analyzers showed a standard deviation better than 0.1 ppb for the 10 min averages. Some analyzers would benefit from improvements in temperature stability to reduce the instrument drift, which could then help in reducing the frequency of calibrations. For most instruments, the water vapor correction algorithms applied by companies are not sufficient for high-precision atmospheric measurements, which results in the need to dry the ambient air prior to analysis.

scholarly journals Long-term Exposures to Air Pollutants Affect FeNO in Children: A Longitudinal Study

2021 ◽  
Author(s):  
Yue Zhang ◽  
Sandrah P. Eckel ◽  
Kiros Berhane ◽  
Erika Garcia ◽  
Patrick Muchmore ◽  
...  
Keyword(s):  
Air Pollution ◽  
Air Pollutants ◽  
Ambient Air ◽  
Short Term ◽  
Annual Average ◽  
Respiratory Effects ◽  
Early Marker ◽  
New Evidence ◽  
Short Term Effects

ABSTRACTFractional exhaled nitric oxide (FeNO) is a marker of airway inflammation shown to be responsive to short-term air pollution exposures; however, effects of long-term exposures are uncertain. Using longitudinal assessments of FeNO and air pollutant exposures, we aimed to determine whether FeNO is a marker for chronic effects of air pollution exposures after accounting for short-term exposures effects.FeNO was assessed up to six times 2004-2012 in 3607 schoolchildren from 12 communities in the Southern California Children’s Health Study. Within-community long-term ambient air pollution exposures (PM2.5, PM10, NO2, O3) were represented by differences between community-specific annual averages and the eight-year average spanning the study period. Linear mixed-effect models estimated within-participant associations of annual average air pollution with current FeNO, controlling for previous FeNO, prior seven-day average pollution, potential confounders, and community-level random intercepts. We considered effect modification by sex, ethnicity, asthma, and allergy at baseline.We found FeNO was positively associated with annual average air pollution, after accounting for short-term exposures. One standard deviation higher annual PM2.5 and NO2 exposures (PM2.5:2.0 μg/m3 ; NO2:2.7 ppb) were associated, respectively, with 4.6% (95%CI:2.3%-6.8%) and 6.5% (95%CI:4.1%-8.9%) higher FeNO. These associations were larger among females. We found little evidence supporting association with PM10 or O3.Annual average PM2.5 and NO2 levels were associated with FeNO in schoolchildren, adding new evidence that long-term exposure affects FeNO beyond the well-documented short-term effects. Longitudinal FeNO measurements may be useful as an early marker of chronic respiratory effects of long-term PM2.5 and NO2 exposures in children.Key messagesWe show strong evidence that long-term exposures to air pollutants affect FeNO, independent of the well-documented associations with short-term exposures to air pollutionLongitudinal FeNO measurements may be useful as an early marker of chronic respiratory effects of long-term air pollution exposures in children.Capsule summaryAnnual average PM2.5 and NO2 were associated with FeNO in schoolchildren, adding new evidence that long-term exposure affects FeNO beyond the well-documented short-term effects.

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