Star Date 4: Biological Perspective - Human Hibernation

Imagine an incredible scientific breakthrough that could further the reaches of space exploration, cure obesity, prevent soldiers from dying on the battlefield, ease the process of organ donation, and save the lives of heart attack victims. All of these diverse issues are being combated by the detailed research of top scientists around the world who have become focused on the same goal: human hibernation. The concept of slumbering away for months on end like other organisms has been the center of many science fiction novels, but now, this space age dream is edging ever closer to becoming a realistic solution to many problems.


Throughout the course of history there have been several instances where human beings have been thought to have achieved a state of hibernation. Cases of incidental human hibernation have been open to criticism, but in several instances there is simply no other explanation for how particular individuals survived specific situations.

Take for instance the case of Mitsutaka Uchikoshi, a 35 year old Japanese business man who broke his hip while falling down a mountain during 2004 (Harlow). Mr. Uchikoshi was revived 24 days later at a Kobe, Japan, hospital after being discovered utterly lifeless in a state of frozen coma (Harlow). The doctor who treated the man said: “We don’t know how he survived so long, but his body was preserved in ice for nearly a month and now he is back to normal. If we can understand why, we can save many lives in the future (Harlow).”

Another incident involving accidental human hibernation took place during the winter of 1999 when a Norwegian skier was submerged in icy water for more than an hour (Britt). When the skier was discovered, her heart had stopped while her body temperature had dropped over 40 degrees Fahrenheit (Britt). After receiving medical attention, she fully recovered.

The final incident to be presented took place during a cold winter night in Canada during 2001. Erika Nordby, a toddler, wandered out into the -11 degree Fahrenheit night wearing only a diaper and a t-shirt (Britt). When found, Erika had suffered severe frostbite, and was lacking a heartbeat. After receiving medical attention she was revived, required no amputations, and made a complete recovery (Britt).

All of the afore mentioned victims showed significant signs of hibernation, but without further medical research and testing, there is no way of knowing that a state of hibernation was in fact the preserving life force that saved these three individuals.

The Merriam-Webster dictionary defines hibernation as: “to pass the winter in a torpid or resting state,” or, “to be or become inactive or dormant (Merriam).” When most people consider hibernation, thoughts of bears burrowing down underneath a leafy forest floor to slumber until the warmth of spring arrives are the first to come to mind. In all reality, bears are only one animal of many that hibernate, including ground squirrels, yellow jackets, bats, and, surprisingly enough, the warm-blooded fat-tailed dwarf lemur (Judson). All of these hibernate in varying ways, with a diverse range of tendencies.

For instance, the black bear only has a slight drop in body temperature as it passes into a long term deep and continuous sleep (Judson). During hibernation, bears are easily stirred if their dwellings are tread upon, and they neither urinate nor defecate throughout the course of their stasis. Energy is gained by burning fat stores directly instead of relying caloric intake (Judson).

Other small mammals like ground squirrels experience extreme drops in core temperature that render the organism completely inactive. Throughout the winter ground squirrels will awaken for short stints, usually a few hours, of intense activity (Judson). These organisms will forage for food and warm their bodies during the short intervals of liveliness.

The yellow jacket is only one of many insects that hibernate, largely in part because of their ‘supercool’ nature. No, these insects do not all rock backwards Kangol’s like L.L. Cool J and a fresh pair of Air Jordans, in this instance ‘supercool’ refers to a lack of nucleating agents within the chemical composition of bodily fluids within the organism. This lack of particles around which crystals can form allows these insects to avoid freezing solid as long as there is no outside factors that introduce nucleating agents into their environment (Campbell). Many other organisms are also ‘supercool,’ mainly those which are commonly referred to as being cold-blooded (Judson).

Humans and other warm-blooded mammals do not have the potential to rid all cells of nucleating agents to produce a ‘supercool’ situation (Campbell). The hearts of mammals such as humans are rendered completely unreviveable and inoperable after cooling past 70 degrees Fahrenheit in most common cases (Magleby). This extreme cooling often times leads to heart-failure. Most mammals that hibernate, such as bears, do not drop their bodily temperature more than a few degrees, relying on clockwork interval bouts of extreme shivering throughout the hibernating months. This shivering also helps deter the chronic muscle decay that could be a potential side effect of lying dormant with little movement for months at a time (Judson).

Bears also combat dropping body temperatures by burning fuel, a large endergonic reaction when one considers the substantial difference between the core body temperature of the hibernating mammal and the temperature of the surrounding environment (Judson). In order to facilitate this excessive burning of energy, the body is forced to burn off large stores of fat to compensate for the lack of caloric intake by the slumbering beast. This is the cause of the seasonal weight gain seen in most hibernators, excepting those that rouse to forage for fuel throughout the course of the hibernating season (Thompson). Additionally, some mammals that are known to hibernate rest in warmer climates, a factor that offsets the need for extreme body temperature regulation.

The fat-tailed dwarf lemur of Madagascar was only recently discovered as the first known hibernating primate (Thompson). These mammals hibernate to save energy when food is scarce during the five to seven month Madagascarian dry season. The discovery of the first hibernating primate has spurred on genetic research by Dr. Matthew T. Andrews, professor of biochemistry at the University of Minnesota Duluth (Thompson).

In his research Dr. Andrews has pinpointed two genes that he believes trigger hibernation in mammals. The genes, which are identified as PL and PDK-4, switch enzymes in order to enable the body to burn fat rather than carbohydrates over a long period of extended stasis (Thompson). “In the hibernation genes we have discovered, there are similar genetic sequences with those of humans. It is decades away, but…short-term stasis would be potentially possible after a lot more investigation on the molecular-biological level,” said Dr. Andrews (Thompson).

Genetic progress relies largely on other detailed research projects including advances in gene manipulation therapy and the ability to regulate gene interaction, both projects that are still years from reaching fruition. Alternatives to gene manipulation studies have also had surprising results in some mammals.

Researchers Mark Roth and Fred Hutchinson of the Fred Hutchinson Cancer Research Center in Seattle, Washington have become the first scientists to successfully induce hibernation in mammals (Britt). The researchers successfully utilized hydrogen-sulfide gas to stop all cell-activity in a grouping of mice during a 2004 study. This process essentially transformed the group of mice temporarily from warm-blooded to cold-blooded organisms. The hydrogen-sulfide gas was given through the respiration process, and caused a completely and utter shut down of all cell activity in the mice (Britt). After lying seemingly lifeless for six hours the mice were revived by simply switching their air supply back to a concentrated stream of oxygen (Britt). The most negative aspect of this potential for human hibernation is the natural tendency of hydrogen sulfide gas to be poisonous in significant amounts, making the quantities to be inhaled a tricky and high-risk venture (Campbell). The mice did not seemingly experience any long-range mental side effects, a problem that is of high concern to many considering the feasibility of human hibernation.

Hibernation in some mammals, like the golden – mantled ground squirrel, causes a complete disconnection and disabling of dendrites during their state of suspended animation (Judson). When the squirrels awake, it manages to regrow its dendrites immediately, a process that is largely thought to be unfeasible in humans (Judson). This ‘death of dendrites’ is a side-effect of extreme drops in temperature that cause suspended animation in the squirrels. When this information is paired with the facts regarding heart failure at low temperatures, the feasibility of cold temperature human hibernation seems unlikely. This has led researchers to search for other means by which to achieve the goal of human hibernation.

One such scientist looking for alternatives to the traditional cold-temperature human hibernation theories is Dr. Chen Chi Lee, a biochemist at the University Of Texas Medical School located in Houston, Texas. Dr. Lee was recently awarded a grant totaling over $2.2 million from the National Health Institute to continue his research into 5-prime adenosine monophosphate (5’-AMP) (Magleby). 5’-AMP has been found to induce short hibernation like state in mice. The 5’-AMP acts similarly to the hydrogen sulfide gas method by depriving cells of oxygen to slow the metabolic rate. Manipulation of the monophosphate has proven to be the most difficult obstacle, and Dr. Lee has federal funding through 2013 to continue his research in hopes that he will figure out a way around this problem (Magleby).

Another project being fueled by American tax payer dollars is the research of Dr. Hasan Alam of the Massachusetts General Hospital. Dr. Alam’s research is funded by the United States Army and focuses around a plasma expander solution that rapidly drops body temperature when injected directly into a patient (Thompson). The plasma expander consists of a saline solution that slows metabolism by dropping a patient’s body temperature roughly 27 degrees Celsius in a matter of minutes (Thompson). Dr. Alam has done the majority of his research on eight pigs who he was able to send into hibernation for two hours before reviving them with no noticeable negative side effects (Thompson). As the research continues, Dr. Alam hopes to capitalize on his ties to the U.S. Army and do future testing on soldiers (Thompson).

Without further research that crosses the line from testing nonhibernating mammals to actual clinical tests on humans, the hibernation of human beings will continue to be a space age dream. Many well-educated and driven individuals have taken the time to observe, document, and study the way other organisms rely on this phenomenon for survival and then taken the information gathered and applied it to dedicated and devoted research. Many scientists are taking a variety of approaches to further research in this field including studies on DNA, hydrogen sulfide gas, 5’-AMP, and plasma expander solution, along with a variety of other methods in the hopes that one day it will be feasible to solve many problems and advance the betterment of society by utilizing human hibernation techniques.


References

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