http://news.yahoo.com/s/livescience/[WORD TOO LONG]
Mystery Explained: How Frozen Humans Are Brought Back
When subjected to literally freezing temperatures, the embryos of yeast and garden worms do not live, researchers found. A full 99 percent of those in the experiment died after 24 hours of exposure to temperatures just above freezing.
But, when first deprived of oxygen in the manner described above, 66 percent of the yeast and 97 percent of the garden worms survived. Upon re-warming and reintroduction of oxygen, the "two widely divergent organisms" reanimated and showed normal life spans, said scientists in a statement.
Documented cases of humans successfully revived after spending hours or days without a pulse in extremely cold conditions first inspired Roth to study the relationship between human hypothermia and his own research in forced hibernation.
In the winter of 2001, the body temperature of Canadian toddler Erica Norby plunged to 61 degrees Fahrenheit (16 degrees Celsius) as she lay for hours in below-freezing weather after wandering outside wearing only a diaper. Apparently dead, she recovered completely after being re-warmed and resuscitated.
The same curious fate befell Japanese mountain climber Mitsutaka Uchikoshi in 2006, who was discovered with a core body temperature of 71 degrees F (22 degrees C) after 23 days after falling asleep on a snowy mountain.
"We wondered if what was happening with the organisms in my laboratory was also happening in people like the toddler and the Japanese mountain climber. Before they got cold did they somehow manage to decrease their oxygen consumption? Is that what protected them?" Roth said. "Our work in nematodes and yeast suggests that this may be the case, and it may bring us a step closer to understanding what happens to people who appear to freeze to death but can be reanimated."
Oxygen deprivation's protective effect comes from the way it arrests biological processes before dangerous instabilities can develop. When reanimated, the processes continue where they left off, with no sign of disruption having occurred.
"When an organism is suspended its biological processes cannot do anything wrong," Roth said. "Under conditions of extreme cold, sometimes that is the correct thing to be doing; when you can't do it right, don't do it at all."
The ultimate goal of such research is to "buy time" for patients in physical shock, such as after heart attacks and severe blood loss, increasing their chances of survival by preserving them until they can reach medical care, researchers said in a statement. Other forms of forced hibernation include exposure to chemical agents like hydrogen sulfide.