Human actions have resulted in warming and acidification of the oceans and are now causing increasing hypoxia.

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Back in Minnesota, complementary studies are examining the role of hypoxia in heart failure and the mechanisms involved.

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Of great interest is the physiological pathway called the hypoxia-inducible factor, or HIF, which seems to trigger the body's response to low-oxygen levels in tissue.

WSJ: Mayo Clinic Researchers on Everest Study High Altitude's Effects on the Body

There is insufficient O2 to gulp where he is going, and if there is a breach in his visor the hypoxia will put him in a deadly place.

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And health officials in North East Lincolnshire said there were increasing numbers of elderly people needing medical help after falling in their own homes because of hypothermia and hypoxia.

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The court was told on Friday that Mr Macia had suffered extensive injuries, culminating in hypoxia - a lack of oxygen supply to the body - causing his death.

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Such bleeding may deprive the baby of oxygen - a condition known as fetal hypoxia - and this is turn impacts upon the developing brain, potentially raising the risk of autism.

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Chronic hypobaric hypoxia (lack of oxygen): where the expedition will encounter equivalent altitudes up around 3, 800m due to the extreme cold temperatures and distance from the Equator which further decreases atmospheric pressure.

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