Squirrels help to store organs

September 22, 2000

The biochemical tricks that the ground squirrel uses to hibernate through the Canadian winter may herald new ways to prolong the shelf-life of human transplant organs.

Kenneth Storey and colleagues at Carleton University, Ottowa, Canada, are systematically revealing the genes and enzymes behind mammalian hibernation.

This may help scientists devise techniques to prevent organs such as hearts from suffering damage when chilled.

However, Storey's research makes the prospect of being able to "cold store" humans for long space flights or in transit to wartime field hospitals appear an unlikely prospect.

Mammals that hibernate to survive the cold temperatures and scarcity of food during winter months suppress their metabolic rate severely, allowing their body temperature to fall to near ambient levels and living off fat reserves. The ground squirrel's metabolic rate can fall to as little as 4 per cent of its active level.

Using gene chip technology, Storey's team has analysed 1.6 per cent of the animal's genome to reveal which genes within that sample get turned on and which are turned down within the animal's heart when it hibernates. Their preliminary results are published in the latest issue of the journal Cryobiology.

Despite being in torpor, the rodent's heart must keep blood pumping around its body, beating at a much slower rate than normal but with more force.

Storey found that while most genes were either unchanged or turned down during hibernation, several other families of genes came to life, some of which were linked to the mitochondria, the cellular power stations, and others to reconfigure each cell's internal chemistry to its new state.

"If the preliminary chip results hold up, it would be fair to hypothesise that only several hundred genes are turned on during the cool-down and hibernation phases. There are likely to be a limited number of hibernation-specific 'switches' involved in controlling tissue function," Storey says.

If a human were subjected to similarly low temperatures, his or her heart would abruptly stop beating. But it is probable that humans possess many of the same genes and proteins that the ground squirrel uses to switch to hibernation mode. Our species just lacks the ability to string together the complex combination to produce the desired effect.

Storey's biochemistry research shows that these genetic changes are paralleled by a cascade of protein formation and a process called reversible protein phosphorylation that reduces the activity levels of key enzymes and slows the ion pumps in every part of the cell.

Storey believes the complexity of these interactive processes and the fact they vary in different organs make it unlikely that humans will ever be able to hibernate - there is no simple master switch that can be flicked.

Sense of self is a fragile thing A former US marine who believed he was a living cartoon character is teaching psychologists about the fragility of human self awareness and personality.

The man adopted an entirely new personality after the right frontal lobe of his brain was damaged on the operating table a decade ago.

James Slaughter, head of psycho-somatic medicine at the University of Missouri-Columbia in the United States, and colleagues believe the case, published in the journal Brain Injury, illustrates how this part of the brain plays a key role in our self-perception.

When Mr D, a 28-year-old Gulf war veteran, he arrived at the University of Missouri's rehabilitation centre in 1999, he believed he was a cartoon character called "Hockey Stick" who was trapped in Mr D's body.

"He seemed to view himself as an almost two-dimensional character, like a cartoon on a page, and although there was some awareness that someone else had once occupied the body, he never deviated from this belief," Slaughter said.

The patient had constructed a bizarre world that involved an evil old lady who had taken over his mother's body and missions into space to rescue dead babies from Satan. He was also occasionally aggressive, heard voices that told him to kill and socially and sexually inappropriately.

Nevertheless, he was well aware that he was in hospital being treated to improve his poor gait, another consequence of his post-operative damage, and was alert, co-operative and recognised his father and physicians without difficulty.

The treatment Mr D received at the university improved his ability to walk, helped end his hallucinations and tackled his emotional difficulties, but his belief in his identity as a living cartoon and the illogical world he thought he lived in never wavered.

The large lesion in his brain's right frontal lobe has been identified as one of the causes of delusional misidentification syndrome, a condition that has been documented in about 600 cases.

"Most people just accept that awareness of self is innate and invariable in all of us, but this case shows how a disturbance in the right frontal lobe can disrupt this view, breaking that which makes us continuous with our past history and future," Slaughter said.

Uranus's moon tally grows Astronomers have discovered three new moons orbiting Uranus, putting the planet at the centre of the most populated planetary satellite system known.

The results of a year-long search by an international team led by Brett Gladman from the Observatoire de la Cote d'Azur in Nice, France, gives the aquamarine gas giant a flotilla of 21 companions for its 84-year journey around the Sun.

The scientists have named the new moons after characters from one of William Shakespeare's most mystical plays, The Tempest - Prospero, the sorcerer, Setebos, the spirit and Stephano, the bewitched butler.

They join Caliban, the savage, and Sycorax, the witch, two more Uranian satellites named from Tempest characters and discovered by Gladman and colleagues in 1997.

All are irregular moons with orbits that are either very non-circular or highly inclined to the planet's equator.

Each is thought to be just 20km in diameter and were probably captured by the planet's gravity during its formation some 4.5 billion years ago.

Astronomers believe Uranus, a gas giant a third the size of Jupiter, 3 billion km from the Sun, may have had a particularly turbulent nativity, with its axis of rotation tipped by 90 degrees, its magnetic field skewed and evidence of great violence scoured into the surfaces of its regular moons.

Gladman's team used the world's largest electronic camera, the CFH12k at the Canada-France-Hawaii Telescope on Muana Kea, Hawaii, to search a region around the planet where it had been predicted satellites would most likely be found.

Their efforts were rapidly rewarded when they got their first glimpse of the three faint moons in July 1999.

However, they would have to wait another year before they could confirm their discoveries as, to prove the objects were indeed satellites of Uranus and not merely passing rocky bodies, they had to capture images of all three a second time at different points in their orbits.

The team used observing time at a number of observatories around the world before they were able to gather sufficient data to finally register them with the International Astronomical Union as genuine moons last month.

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