Monthly Archives: November 2012

Mental itching is a real head-scratcher

Two recent studies show that an itch can be caused just by watching someone else scratch, or by looking at pictures of itchy things.

The first involved 51 participants watching videos of others scratching, while scanning their brains to see which parts were activated. Interestingly, watching someone else scratch switched on the same areas of the brain as scratching yourself (Holle H, Warne K, Seth AK, Critchley HD & Ward J 2012, “Neural basis of contagious itch and why some people are more prone to it”, Proceedings of the National Academy of Sciences, vol. 109, no. 48, pp. 19816-19821, doi: 10.1073/pnas.1216160109).

It’s tempting to think this is related to empathy, but in fact those most susceptible to induced itching were the more neurotic members of the group. So it appears to have more to do with one’s own hang-ups than an ability to put oneself in others’ shoes.

Close-up of a bull ant, found in bushland surrounding Swifts Creek, Victoria (click to embiggen)
Bull ant from the genus Myrmecia, found in bushland surrounding Swifts Creek, Victoria – actual size is around 25 millimetres. Are you feeling itchy yet? (Photo by Fir0002/Flagstaffotos)

The second study had 30 participants looking either at itch-related pictures, like ants, fleas or skin conditions, or neutral images, like butterflies or healthy skin. Once again, there was a strong correlation between feelings of itchiness or actual scratching, and the nature of the images (Lloyd DM, Hall E, Hall S & McGlone FP 2012, “Can itch-related visual stimuli alone provoke a scratch response in healthy individuals?”, British Journal of Dermatology, published online 22 November 2012, DOI: 10.1111/bjd.12132).

The researchers of this study concluded that this shows evidence of the involvement of so-called ‘mirror neurons’ – those brain cells that respond equally to performing a task and watching someone else perform the task – but they point out that the fact that only pictures of stimuli were involved, it’s more than just mimicking behaviour.

Either way, it seems that the urge to scratch can be as much a matter of perception as it is of the presence of a genuine irritant.

(This story aired on 29 November 2012 – you can listen to the podcast.)

Asbestos, the Fiend’s fibre

The ABC TV mini-series Devil’s Dust gave an enlightening but frightening history of asbestos-related disease and litigation in Australia, and it made me want to find out more about this wonder material turned bad. What exactly is asbestos, and how does it cause cancer?

A piece of blue asbestos compared with a 1 centimetre rule, showing how it's composed of tiny fibres (click to embiggen)
Blue asbestos, or crocidolite, mined at Wittenoom, Western Australia. The ruler measure is 1 cm, giving an idea of the tininess of the fibres (Photo by John Hayman, via Wikimedia Commons)
Asbestos is a family of fibrous minerals. The most common type mined in Australia, primarily at Wittenoom WA, was blue asbestos, or crocidolite. Its chemical formula is Na2Fe2+3Fe3+2Si8O22(OH)2, which is actually that of an igneous mineral called riebeckite. Riebeckite forms elongated blue crystals, but it’s only considered asbestos when the crystals are fibres with a width of about 1 micrometre or less.

There are five other types of asbestos, mostly minerals with tiny rigid fibres like crocidolite. However, there’s one kind, known as white asbestos or chrysotile, mined primarily in Canada, which has longer, softer fibres.

All kinds of asbestos are resistant to fire, heat and chemical damage, and have been used in various forms for thousands of years. However, it’s probably the flexible white asbestos, chrysotile, which was woven into miraculous cloths that could be cleaned simply by throwing them into the fire. Wily traders tried to convince people these cloths came from the fur of the fireproof salamander, but Marco Polo himself debunked the idea, calling it “fabulous nonsense”.

In Australia, the less flexible blue asbestos was used for decades as a component in building material and insulation, thanks to its good tensile strength. But there have been other uses that seem absolutely crazy in hindsight, such as making filters for cigarettes and gas masks, or even artificial snow.

Comic panel showing Johnny Storm, the Human Torch, who lived in a specially designed room with asbestos wallpaper, carpet and bedspread, just in case he burst into flame while he was asleep (embiggen)
Johnny Storm, aka the Human Torch, had the superpower of bursting into flame and so for safety he basically lived and breathed asbestos. Of course, he got his powers through exposure to radiation, so maybe ‘safety’ is subjective. (Strange Tales #101, 1962)

However, health problems due to over-exposure have been known for hundreds of years, with mentions of lung disease afflicting slaves who worked in asbestos mines. Quite possibly this was asbestosis, which is scarring of the lungs caused by an accumulation of inhaled fibres.

Even scarier though is mesothelioma, a cancer of the mesothelium, or protective lining around organs – primarily the pleura, which lines the lungs.

How asbestos causes cancer – or even how it gets out of the lungs and into the pleura – is not exactly known. There are theories that it causes inflammation, or oxidative stress due to the undigestibility of the fibres, or that it interferes with signalling mechanisms, or even that the fibres get physically tangled and interfere with chromosomes in the cell (Toyokuni S 2009, “Mechanisms of asbestos-induced carcinogenesis”, Nagoya Journal of Medical Science, vol. 7, no. 1, pp. 1-10).

This is because one notable property of asbestos fibres is that, even though they start at a scale of around 1 micrometre, they easily break up into into thinner fibres, getting down to 0.01 micrometres, or 10 nanometres. That’s smaller than the pores in cell nuclei.

Whatever the mechanism, it seems that it can only take one rogue asbestos fibre to give you cancer. So should you panic?

Well, although there are about 600 new cases of mesothelioma diagnosed in Australia every year (based on 2007 data), that doesn’t necessarily reflect the ubiquity of asbestos in the community. Some people contract mesothelioma after minimal exposure, such as washing clothes or being near a building site, but some workers in asbestos plants don’t get the disease. It’s possible that most of the fibres are removed by the human body before they’re able to do lasting damage.

That doesn’t mean you should be too complacent, as mesothelioma can take between 20 and 50 years to develop following exposure. But neither should you panic: when the dangers were first realised, there was a rush to remove asbestos from buildings, but this only led to more fibres being released into the air. So now the recommendation is that, if the asbestos is intact, it’s safer to leave it where it is.

But if you are doing renovations and need to remove it, it’s important to follow appropriate safety precautions, or hire a qualified contractor. You can find information about safe removal of asbestos at Asbestoswise, www.asbestoswise.com.au.

Asbestoswise also recommend not panicking if you accidentally disturb and break some asbestos. Their advice is to wipe up the dust with a damp cloth or paper towel, put the cloth or towel into a plastic bag, tie the plastic bag and put it into another plastic bag, tie up that one and put it in your rubbish bin. Seal any cracks in the panel, or if it’s too damaged, replace the whole thing.

So asbestos is very scary, but you don’t need to panic – just treat it with caution.

You can find out more about mesothelioma from the Cancer Council Victoria.

(This story aired on 29 November 2012 – you can listen to the podcast.)

So you think you can make a super-alloy

You might think that science lacks the raw power of interpretive dance, but worry no more. Dance Your PhD is a yearly competition where scientists get to try a style of communication that’s a bit more active than peer-reviewed journals.

This year’s winner is Peter Liddicoat from the University of Sydney, who explained his PhD thesis on the nanostructure of aluminium alloys by using a circus strongman, a unicyclist, jugglers and clowns.

Now known as Dr Liddicoat, Peter won $1000 and a trip to Belgium for a screening of his dance at TEDxBrussels.

Of course, $1000 doesn’t go very far in scientific research, but Dr Liddicoat and his colleagues are using the publicity to help with their crowd-funding campaign to build an atom microscope for biology. You can find out more about that at www.indiegogo.com/atom-microscope

On our show that aired on 22 November 2012, Beth spoke to Dr Liddicoat about his research and his dance – you can listen to that interview on our podcast.

Great Barrier Reef coral loss is probably our fault

The Great Barrier Reef is the largest coral reef system in the world, stretching over 2,600 kilometres along the coast of Queensland and covering an area of 344,400 square kilometres. But over the past 27 years it’s lost half its coral, apparently thanks to human activity.

Researchers from the Australian Institute of Marine Science in Townsville have been monitoring the amount of coral since 1985. Back then, the reefs they studied had 28% coral cover, but in 2012 they only had 13.8%. That’s a reduction of 50.7% (De’ath G, Fabricius KE, Sweatman H & Puotinen M 2012, “The 27–year decline of coral cover on the Great Barrier Reef and its causes”, Proceedings of the National Academy of Sciences, vol. 109, no. 44, pp. 17995-17999, doi:10.1073/pnas.1208909109).

This reduction wasn’t uniform across the whole system, as the far northern reefs have remained fairly stable at about 24% coral cover. But there’s been a decline in the central region – which they classify as between Cooktown and Mackay – and in the southern region below Mackay, where there’s been a steep drop of over 75% in the past decade alone.

The researchers also looked at what caused these reductions, by modelling possible causes against the observed fluctuations in coral cover. What they found was that 48% of the coral reduction could be attributed to tropical cyclones, 42% to outbreaks of crown-of-thorns starfish, and 10% to mass coral bleaching (primarily two events, in 1998 and 2003).

Climate change would seem to be a factor here, as it’s been linked to the increasing intensity of tropical cyclones (see Knutson TR, et al. 2010, “Tropical cyclones and climate change”, Nature Geoscience, no. 3, pp.  157–163, doi: 10.1038/ngeo779 [PDF 641 KB]).

Temperature also seems to be a major cause of coral bleaching, which is when the coral loses its symbiotic zooxanthellae. These single-celled organisms photosynthesise and provide energy for the coral polyps – as well as the vibrant colours of the coral. In turn, they get nutrients and a home. However, the zooxanthellae seem to be sensitive to temperature, as a rise of only 1°C  can cause mass deaths of them and subsequently their host coral.

But even though climate change is the biggest culprit, the researchers admit it’s unlikely that in the near future we’re going to make a big impact or reduce temperatures. So instead, they suggest concentrating on the crown-of-thorns starfish. If we could cut out just the starfish, but cyclones and bleaching continued, the coral cover would still increase by 0.89% per year.

And we have a chance of doing this, because the crown-of-thorns starfish itself is influenced by human activity.

Crown-of-thorns starfish competing to eat the last remaining piece of coral (click to embiggen)
Crown-of-thorns starfish, Acanthaster planci, competing to eat the last remaining piece of Acropora coral (Photo by JSLUCAS75, via Wikimedia Commons)
As the name suggests, the crown-of-thorns, or Acanthaster planci, is a spiny starfish, or sea star. It’s the second-largest species of sea star in the world, with adults reaching 25-35 cm in diameter and having up to 21 arms. It feeds by latching onto coral with its multiple tube feet and then extruding its stomach out through its mouth to digest coral polyps.

It sounds like a nasty, introduced species, but actually it’s been in the Great Barrier Reef for at least 8000 years. In fact, it’s found in coral reefs across the Indian and Pacific Oceans, from the coast of Africa to the coast of America.

And at normal population numbers, it seems to be a natural part of the reef ecosystem. It prefers to eat the faster-growing coral species, giving the slower-growing species a chance to compete. But occasionally the numbers increase to plague proportions, and the starfish have to eat everything.

Now it’s not 100% certain what causes these outbreaks, but the leading theory is that it’s due to water quality. The starfish larvae feed on phytoplankton, and phytoplankton numbers increase with inorganic nutrients in the water. And these inorganic nutrients increase greatly when fertiliser is washed off farmland, particularly after floods.

So the researchers recommend more effort to improve water quality in order to reduce the numbers of crown-of-thorns starfish. This is in preference to hunting them down one-by-one – which is favoured by MP Bob Katter – because in the past that’s proven to be rather expensive and labour-intensive, but overall ineffective across the whole reef (although hunting does work for protecting a small area, so it’s good for tourist operators).

In the end, it all comes down to pollution, whether greenhouse gases or fertiliser run-off. And until we can cut the former, we need to concentrate on the latter. The crown-of-thorns starfish may in fact be a natural feature of the Great Barrier Reef, but it’s our activities that turn it into a threat.

(This story aired on 22 November 2012 – you can listen to the podcast.)

Synaesthesia mixing the senses at MONA

On 3 and 4 November 2012, I was lucky enough to visit Hobart’s Museum of Old and New Art (MONA) and enjoy a two-day event that mixed art and science to explore the psychological phenomenon of synaesthesia.

Synaesthesia is a ‘joining of senses’, where you perceive something with one sense and at the same time you experience it with another sense. For instance, you may see colours and shapes when listening to music, or colours associated with particular letters or numbers.

MONA’s Synaesthesia event represented this concept with the Tasmanian Symphony Orchestra playing music from composers such as György Ligeti, Henryk Górecki and Modest Mussorgsky, as well as performances from Brian Ritchie, Kate Miller-Heidke and Meow Meow. It blended this with visual art from the museum’s exhibitions, a film program, including Jonathan Fowler’s Red Mondays & Gemstone Jalapenos, embedded above, and fantastic catering.

It also included a panel discussion on the topic, with synaesthetes Andrew Legg and Margaret Hollis, pianist and music scholar Peter Hill (representing the synaesthetic composer Olivier Messiaen), and University of New South Wales psychologist Dr Karen Whittingham.

After the discussion, I had the pleasure of speaking to Dr Whittingham about her research on synaesthesia, as well as artist and synaesthete Steve Glass. You can listen to this interview on our podcast from 15.11.2012.

A transcript follows after the break…

Continue reading Synaesthesia mixing the senses at MONA