Member's Corncbr By Drs Barry Feiglin and Peter Parashos (Written by Barry, authorised by Peter)

A Thrilling Trip To Antarctica! Endodontists Very Down Under The jet engines rewed up and we were on our way down the runaway for the most exhilarating trip we had been on for a long time!

It takes approximately 4 hours to get to the Antarctic mainland; about 3000 kilometres South of Hobart. After 3 /* hours flight you can see the first icebergs - the start of the huge continent called Antarctica.

We flew down directly over Tasmania. and the tour guide (four people who had been in Antarctica came along as tour guides) spoke to the radio operator at Macquarie Island - she, like everyone else down in the Antarctic regions, was busily doing maintenance on their buildings and other equipment because the summer time is the only time to do it, and the summer is so very short. This Island in the 5605 latitudes is a sub Antarctic Island. but never-the-less, it gets pretty cold and windy down there! Part of the state of Tasmania. it is I500 kilometres south east of the island of Tasmania and I300 kilometres north of the Antarctic continent.

A few minutes later. we spoke to the radio operator at Casey station (66OS latitude). which is one of the Australian bases on Antarctica - it was really interesting listening to what he had to say about how they were operating there; how different groups had gone off to study different aspects of Antarctic life. For those that are interested, a brief run down of all the different bases in the Antarctic region can be investigated on the Internet on http://www.antdiv.gov.au. .

We continued to fir &th until we reached the South Magnetic Pole (some distance off the coast of Antarctica at 65OS latitude) where we witnessed the needle of the compass spinning out of control - a bit difficult if you want to know which direction you are heading - fortunately. the aircraft has other means of direction control!

And very soon afterwards we encountered the first of a multitude of icebergs - some of them are just so enormous and you

kr ry Feghn (lefi) and h t e r Poroshos on boord the Antorctic .Express.

The l ine shows the extent of our journey.

must realise that more than two thirds of them are beneath the water. Then we reached the pack ice, which is ice that has temporarily broken away from the sea ice, which is about 600 kilometres wide, surrounds the Antarctica continent completely, and trebles the size of Antarctica in the winter time. It was approximately 200 kilometres wide when we saw it.

Antarctica is the world's driest continent with a mean annual equivalent of only 5 centimetres (2 inches) of rainfall. This is lower than the precipitation in most desert areas. It is also the windiest continent, the highest continent and of course the cddest continent - a temperature of -89.6OC was recorded at the Russian base in Antarctica in 1995. In summer time, the temperatures on the Antarctic plateau reach -4OOC. The katabatic winds commencing in the mountainous plateau areas of Antarctica and flowing down towards the sea blow pretty constantly at 70-80 kilometres per hour (gale force) and can often reach speeds of over 250 kilometres per hour in a blizzard! Almost 98% of Antarctica is continental ice and 2% is barren rock. We flew adjacent to Mt. Minto which is 4 I60 metres above the ice but the highest peak is approximately 5 I00 metres above the ice. The thickest ice is nearly 5 kilometres deep!

Antarctica formed about 90 million years ago from the great southern continent called Gondwana. Thus a lot of the fossil and geologic formations are the same as those found in Australia, South East Asia and India.

Australia occupies about 40% of the continent of Antarctica which is about the size of Australia minus Queensland. The continent has a population varying between 4500 people in the summer time to I OOO people in the wintor time.

We encountered the Antarctic mainland at a French base called Dumont d'Urville (see map) - it had a lot of small red coloured

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buildings and an airbase that is no longer used because it was destroyed in part by mountainous seas some years back. The air is so clean and clear down in the Antarctic region that we were able to see for over 100 kilometres. At the coast you can see the sea ice plunging down to the sea, often a distance of 200-300 metres - it is very stark and the treacherous nature of the geography is brought to reality. What looks like small cracks in the ice are often crevasses 100 metres deep - once you fall into one of them you have very l i l e chance of getting out.

We flew down along Commonwealth Bay, where we saw Mawsons Hut (Mawson was one of the pioneers of Antarctica) and Gadget Hut (where the Mclntyres and others have stayed for a year in isolation since 1996 - isolation because nobody can possible reach them in the winter time!) and from there down to Mctoria Land via Mertz's Glacier and Ninnis's Glacier (both Mertz and Ninnis died in one of Mawsons expeditions) and the Transantarctic Mountains and the famous Tucker Glacier that merges into the Ross Sea at a speed of about I kilometre per year. The largest glacier in the world is located between Australia's Mawson and Davis stations, and fills a massive valley 400 kilometres long, 80 kilometres wide and a maximum depth of 2.5 kilometres - enormous!

The Ross Sea is about lo00 kilometres into the Antarctic continent and the South Geographic Pole is a further 1400 kilometres "south" of that!

Antarctica has a wide variety of fish, seals, the famous penguins and bird lie, but during the winter time they all leave and Antarctica is completely desolate.

Antarctica is such a HUGH continent - about twice the size of

Spectacular wght of enormous masses ofpock ice brokrng m y from the seo ice

Australia and as a consequence, It was only possible to see a small fraction of it. But even that small fraction was truly magnificent A video camera was mounted on the nose of the aircraft, so it was possible to see the entire landscape.

The flight back covered some of the coastal areas that we had not seen before and particularly interesting was the grey "oily" areas in the sea ice which are areas of sea ice that had re-joined once again and are separated by ice two to three days old - really fascinating.

We amved back home after I I 1, hours of flying satisfied that we had been on one of the true adventures of a lifetime!

Personal Pain A Single Gene May Account For Individual Sensitivities

People have very different tolerance levels to pain; the same needle may feel like a pinch to one person and an ice pick to the next. Certainly, part of how people perceive pain depends on expectations, fears and other psychological influences. But scientists have now gathered more evidence that pain sensitivity has a strong physical basis as well. Pam can be thought of as a genetically regulated problem. George R. Uhl and his colleagues, lchiro Sora and Zaijie Wang. of Johns Hopkins Universty and the National Institute on Drug Abuse (NIDA) zeroed in on the gene encoding the mu opiate receptor - sections of which they first identified a decade ago. This receptor binds not only with the body's natural pain-killers, endorphins. but also with morphine and other opiate drugs, such as heroin. What they found were striking variations among individuals, which they presented at a National Academy of Sciences' colloquium in December 1998 and reported in the July 6th I999 issue of the organisation's proceedings.

In their initial round of experiments, the group compared stretches of the mu opiate gene in eight different strains of mice. The key differences they uncovered lay within regions of the gene that regulate how many receptors are made. Those animals with more active forms of the gene had higher numbers of mu receptors in their tissues - and higher tolerances for pain. Uhl and co-workers then produced mice that had half the normal number of opiate

receptors and as a result, experienced greater discomfort when exposed to a standard mildly painful stimulus. Knockout mice, which completely lacked the gene and so manufactured no mu opiate receptors, were all the more sensitive. The work further showed that the fewer receptors, the less responsive the animals were to morphine.

The next step was looking at humans. "PET scans have demonstrated that some individuals have twice as many mu opiate receptors in certain brain regions as others. The receptors in the human brain are concentrated in the thalamus (involved in pain), the cerebral cortex, the visual cortex and the basal ganglia, which coordinates movement and emotion. The number of receptors varies dramatically among individuals, probably owing to genetic differences. Additional research has uncovered gender differences: women appear to have more kappa opiate receptors, which also bind with endogenous pain killers. The results could help scientists develop pain medications that are tailored to each individual patient's genetic make-up. And they could make it possible to predict a person's individual risk for developing a drug addiction.

Scientific American, July 26, 1999 httpJ/www.sciam.com/ucploratiocrr/ I 999/072699painlind ex.html

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