Australasian Science: Australia's authority on science since 1938

Exclusive subscriber content

By Stephen Luntz

Subscribe for complete access to dozens of Browse articles and features each month.

Mint Relief of IBS Revealed
The mechanism by which peppermint soothes gastro-intestinal pain has been found, opening the way to more potent protection.

Peppermint tea has long been a folk remedy for stomach pains, and clinical research has found a benefit. Some countries now allow peppermint extracts to be sold with therapeutic claims although the mechanism of relief remains unknown.

In work published in Pain, Dr Stuart Brierley of Adelaide University’s Nerve–Gut Research Laboratory used a concentrated version of the peppermint component icilin to seek the channel by which the body responds.

“Our research shows that peppermint acts through a specific anti-pain channel called TRPM8 to reduce pain-sensing fibres, particularly those activated by mustard and chilli. This is potentially the first step in determining a new type of mainstream clinical treatment for irritable bowel syndrome,” Brierley says.

The body has a large family of related ion channels that respond to different herbs, of which TRPM8 is one.

Brierley says he does not know if icilin appears in any other plants, but thinks it is rare. He says he chose to study icilin because peppermint’s cooling sensation is well-known, and the clinical evidence for peppermint’s effectiveness indicated it was a promising line of research.

Having established the mechanism, Brierley hopes to be able to identify which forms of irritable bowel syndrome are most likely to be susceptible to peppermint treatment, as well as finding an even more potent version for over-the-counter medications.

Vaccine Developed for Hendra Virus
CSIRO’s Australian Animal Health Laboratory (AAHL) has been successful in the search for a vaccine against the Hendra virus.

The Hendra virus exists in fruitbats and is occasionally transmitted to horses, which in turn can transmit it to stablemates or to humans in close proximity. A few dozen horses are known to have died from the disease, along with four people. However, Hendra virus has aroused concern well in excess of these numbers because the fatality rate is so high – the four deaths come from just seven infections.

“Our trials so far have shown that the vaccine prevents the infection of horses with Hendra virus,” says Dr Deborah Middleton of AAHL.

The vaccine was made after recognising that the G protein on the virus’ surface is an essential part of the virus against which antibodies can be mustered. “There’s nothing special about the way it was done,” says Middleton. “The real challenge is that this is a biosafety 4 disease, along with ebola, so all the research needed to be done in a biosafety level 4 facility. There’s not many of those in the world, and only one in Australia.”

The vaccine has no such dangers, having been made artificially in a cell culture. Middleton says “it’s never been near a live virus”.

Clearing a vaccine for equine use can be quicker than for humans, and it is hoped it may be available in 2012 if field trials prove successful.

Nipah virus, a close relative of Hendra, has caused 100 deaths in South-East Asia. Middleton says: “For once luck is on our side. Cross-reactivity works in favour of Hendra, so a vaccine raised against Hendra is likely to work against Nipah, while the reverse is less true”. So far, however, AAHL’s vaccine has not been tested against Nipah virus.

Middleton hopes that all horses in the coastal regions of Queensland, where most outbreaks have occurred, will be vaccinated. “At the moment horses exported overseas need to have tested negative for the Hendra virus antibody. It’s likely this will change to require them to have been vaccinated.

Anti-Cancer Smart Bomb
An artificial antibody, or aptamer, that can target cancer stem cells could transform the fight against the disease, says its maker Prof Wei Duan of Deakin University’s Nanomedicine Program.

“Current cancer treatments destroy the cells that form the bulk of the tumour, but are largely ineffective against the root of the cancer, the cancer stem cells,” Duan says. “This suggests that in order to provide a cure for cancer we must accurately detect and eliminate the cancer stem cells.”

Duan is hoping to create what he calls a “smart bomb”, with one component that detects cancer stem cells and another that destroys them. “The aptamer acts like a guided missile, targeting the tumour and binding to the root of the cancer,” he says. The next stage is to attach a fat particle that can carry anti-cancer drugs to where they are most needed.

Even if this is unsuccessful, adding radioactive compounds to the aptamer could enable cancers to be picked up and located much earlier than is possible at present.

Hyperactive Neurons Lead to Tinnitus
People who experience tinnitus persistently hear noises that are not really there, with roaring and hissing sounds described as well as the more famous ringing in the ears. The most common cause is overexposure to loud noise. It is not usually possible to reverse tinnitus, although the effect of the condition can be reduced with soothing sounds or distraction techniques.

Tinnitus is associated with hyperactive neurons in the dorsal cochlear nucleus. The neurons fire even when there is no external input. However, a team at the University of Western Australia’s School of Biomedical, Biomolecular and Chemical Sciences found that the same hyperactivity occurs in the ventral cochlear nucleus.

A/Prof Wilhelmina Mulders says the activity is not easy to detect on MRI scans as only a small number of neurons are hyperactive, but these are associated with the frequencies at which hearing loss occurs. “We placed electrodes in the brains of anaesthetised animals and detected the hyperactivity at the level of the individual neuron,” Mulders says. The animals have hearing loss, and also behave as if they can hear sounds when no noise is present.

The biochemistries of the ventral and dorsal cochlear nuclei are somewhat different, and this has led the researchers to speculate that it may be possible to find drugs to control the hyperactivity even though this has not yet been demonstrated in the dorsal region.

Mulders stresses that the association between tinnitus and activity in a region does not demonstrate causality. “It may be that another region of the brain is triggering this,” Mulders says. Nevertheless, she hopes that “if we can establish a direct link between this increased brain cell activity and tinnitus we may be able to move a step closer to finding a way to treat tinnitus”.

The hyperactivity appears to be a result of an imbalance of chemicals that excite and inhibit electrical activity. Mulders suggests that methods to stimulate the inhibitory chemicals might prove effective.

The research was published in the Journal of Neuroscience.

Solar Crop Dryers Reduce Waste
A project demonstrating that solar crop dryers can be made largely from local materials may generate substantial benefits for Vanuatu and potentially throughout the Pacific.

Mangoes and nangai nuts grow in great profusion on Vanuatu. Both are in demand in the capital, Port Vila, but transport over poor roads is a problem.

One solution is to dry the produce at the source, but any equipment must be small-scale and low energy. Telia Curtis, a Masters student at the University of NSW School of Photovoltaic and Solar Engineering, adapted a German solar design so it could be made from bamboo, wood, corrugated iron and polythene film. “I want to create a design that could be built out of easily accessible materials,” Curtis says, although solar panels and other electronics will have to be imported.

The dryers capture heat from the sun under the film, and use small photo­electric panels to drive fans that force air over the food, removing moisture. The nuts go rancid if not roasted but drying fruit in direct sunlight can damage it, which is something the dryers avoid.

Dryers distributed around the remote parts of the islands would allow food that currently goes to waste to be treated so that it could survive transportation to the city or even overseas.

“People were so excited,” says Curtis of a demonstration. “It’s particularly great for women because they are the ones that sell foods through the local markets. Mango, paw paws, tamarind and nangai nuts. There’s great potential for all of these.”

Curtis’ supervisor, Dr Richard Corkish, admits that the project was not as successful as some had hoped, with some locally available materials not surviving the tropical conditions. Nevertheless, a store owner in Port Vila has indicated that he could be exporting food to China if a network of dryers can be established.

Corkish hopes it may be possible to create dryer kits that could be sold to villages using microfinancing. However, at the moment the project is unfunded and will probably need grants to take off.

Power Naps Really Do Save Lives
Evidence has been produced to support road safety campaigns calling for people to take a 15 minute “power nap” when driving while tired.

Chris Watling of Queensland University of Technology’s Centre for Accident Research and Road Safety asked 20 people in their early twenties to watch a video of driving on real roads. He then asked them to push a button when they recognised a hazard, and measured their response time.

“Hazard perception is a very important driving skill, and it has been shown to be the only driving skill that has a consistent relationship with crashes,” Watling says.

All those involved in the trial were suffering mild sleep deprivation. They watched the video for 2 hours, with EEG electrodes measuring their sleepiness.

Half the participants then took a 15-minute break, including 10 minutes of brisk walking, while the other half attempted to sleep for 15 minutes.

While the walkers reported that they felt less sleepy, this was an illusion. “The rest break group showed a significant increase in the time it took to respond to potential hazards – an increase of more than half a second,” Watling says. “This increase in reaction time corresponds to travelling approximately an extra 10 metres at 60 km/h and an extra 16 metres at 100 km/h.”

On the other hand, those who tried to sleep performed as well in the third hour as in the second hour. No control group was included, so it is not possible to know whether anyone who continued watching the video without a break would have done even worse than those who exercised.

Watling is careful to note that the choice of 15 minutes is not arbitrary. If a nap is long enough to let someone slip into slow wave sleep then people can suffer grogginess upon waking, making it even more dangerous for them to drive until this has worn off.

Not all of those who tried to sleep were able to, but Watling says that the sample size was too small to make a comparison of those who were successful with those who merely rested their eyes.

He is now planning to repeat the study with participants who suffer from sleep apnoea.

Sunshine Reduces Falls in Elderly
Vitamin D deficiency is associated with falls among elderly men. Since lack of vitamin D also makes bones more brittle, the combination greatly increases the risk of elderly men suffering debilitating injuries.

“Sunshine and vitamin D are essential for maintaining our physical strength and cognitive abilities,” says Dr Jasmine Menant of Neuroscience Research Australia. “Our study shows the importance of ensuring that vitamin D levels are adequate in all older people, particularly as the benefits seem to extend beyond cognition and the musculoskeletal system to our ability to prevent ourselves from falling.” The finding was published in Osteoporosis International.

Menant says “we can’t be confident of a causal relationship. It’s possible that men who are weaker and have less balance may go outside less, leading to vitamin D deficiency.”

Nevertheless, previous studies have indicated that vitamin D provides benefits for muscles and areas of the brain that are relevant for keeping people upright, so the idea that a deficiency could lead to falls is a plausible theory.

In a study of men aged 70–90 years, Menant found that vitamin D deficiency nearly doubled the risk of falls. No statistically significant association was found for women, and Menant notes that women also experience poorer balance when they are low in vitamin D but the effect is less pronounced.

Although internet searches will sometimes provide advice indicating that as little as 5 minutes exposure to sunlight per day is needed to maintain vitamin D sufficiency, the skin becomes less able to synthesise the vitamin from sunlight with age. Consequently Osteoporosis Australia recommends 2–3 hours per week exposure to sunlight over 15% of the body in winter.

Evidence is growing that vitamin D deficiency is associated with a widening range of illnesses (AS, December 2010, p.5).

Middle-Aged Flabbiness Leads to Dementia
Excessive weight is a risk factor for dementia, according to a study published in Obesity Reviews. While this appears to contradict recent research, the difference may be just a matter of time.

Prof Kaarin Anstey of the Australian National University’s Centre for Mental Health Research reports that people who were overweight or obese between the ages of 40 and 60 have an increased risk of developing dementia once they reach 60.

“We found that, in mid-life, being overweight does in fact increase the risk of Alzheimer’s disease. This risk is even greater for those who fall into the category of obese,” Anstey says. While she found that being very underweight is also a risk factor, this is a much less common problem.

Anstey conducted a metastudy based on 11 research papers. She found that people with a body mass index of 25–30 during middle age were 35% more likely to develop Alzheimer’s disease than those who were of healthy weights. Being medically obese doubled the risk factor.

This may not seem surprising given the numerous other risks associated with obesity. While Anstey admits that fat hormones such as leptin are neuroprotective in animal models she concludes: “This evidence suggests that, while the hormones present in body fat were previously believed to protect cognitive function, excess fat in middle age is in fact extremely harmful”.

Anstey’s work is observational, so she says she cannot draw conclusions on causes. However, she says: “There is a very sensible hypothesis that indirect effects increase hypertension and diabetes, and those in themselves probably or definitely increase Alzheimer’s. Overall caloric intake is also a risk factor. Fat also increases inflammation, and we know this increases the rate of brain ageing.”

Some scientists have argued that many conditions associated with excess weight are actually caused by a lack of exercise or fitness. Anstey says: “We tried to look at this, but there was not enough for a meta-analysis because some studies look at physical activity and others don’t”. However, she doubts that being unfit would represent the whole risk factor.

While Anstey’s conclusions contradict those of Prof Osvaldo Almeida of the University of Western Australia (AS, June 2011, p.15), they may be explained by the fact that Almeida only looked at men over the age of 65.

Anstey and Almeida agree on the seriousness of the obesity crisis for children, adolescents and the middle-aged. Almeida also believes that the benefits of being overweight among the elderly are restricted to those who are mildly overweight, and thinks that it may be men with a BMI of 25–27.5 who are healthiest in this age group.

Proof that Atoms Behave Like Light
Research at the Australian National University has confirmed that atoms guided by laser beams behave similarly to light travelling through an optical fibre.

“In an optical fibre, many modes of light can be conducted simultaneously, and they can interfere to produce a speckled pattern of light,” says Prof Ken Baldwin from the ARC Centre of Excellence for Quantum–Atom Optics.

Baldwin is part of a team that trapped a cloud of helium atoms in a laser beam. As they turned the laser’s intensity down, a speckled pattern appeared matching what is observed for light.

The finding was not a surprise. The fact that atoms and photons behave like both waves and particles is a core feature of quantum theory. It has long been expected that the same physics would apply to each, and the behaviour matches a model produced by team member Dr Mattias Johnsson.

However, Baldwin says that previously no one has been able to prove this example of similarity in behaviour.

The team members made the atoms even colder until they became a Bose–Einstein condensate. At this point the speckle disappeared, indicating that the Bose-Einstein condensate was coherent and transmitting a single mode.

The work was published in Nature Communications and follows studies by the same team on the coherence of atomic lasers (AS, May 2011, p.13).

“Matter waves that can be guided like light could be used to create interferometers that can measure very sensitively any external change,” says Baldwin. “For example, tiny changes in gravitational fields. So they could be flown in a plane and detect changes in the Earth’s gravity that indicate the presence of an ore body or a cavern that might contain natural gas.”

Baldwin says that “speckling is an indication that something is going wrong” for both light and guided atoms. Having found it will help those who are constructing applications to eliminate speckling in future.

Desk Jobs Increase Bowel Cancer Risk
People with desk jobs have twice the risk of a form of bowel cancer compared with those who get more activity in their work, according to research published in the American Journal of Epidemiology.

Terry Boyle, a PhD student at the Western Australian Institute for Medical Research, compared the lifestyles of 918 people with cancer aged 40–79 years against more than 1000 controls. He found that working at a desk for 10 years or more almost doubled the risk of cancers of the distal colon and increased the risk of rectal cancer by 44%. There was no increased risk of cancer of the proximal colon.

The causes of cancers in the distal and proximal sides of the colon are different (AS, September 2009, p.6). Colon and rectal cancer have roughly similar frequency in the population as a whole.

While sedentary jobs are becoming more common, recreational activity did not affect the risk. This suggests that sitting, rather than lack of exercise, is the source of the problem.

“Sedentary behaviour appears to be an important risk factor for many chronic diseases,” Boyle says. “It’s important that office workers try to stand and take a break from sitting every 30 minutes, and do things like get up from their chairs and walk down the corridor to talk to colleagues rather than sending an email or making a phone call.”

It is unclear why sitting would increase the risk of bowel cancer, but Boyle says that “some research shows prolonged sitting increases blood glucose levels and reduces insulin sensitivity, both of which are known risk factors for colorectal cancer”.

New Pill Raises Clot Risk
A newer version of the contraceptive pill has a higher risk of blood clots than older versions, according to research published in the British Medical Journal.

Oral contraceptives raise the risk of deep vein thrombosis. If untreated, a blood clot in the legs can break off and travel to the lungs, which can be fatal.

“In absolute terms, we found that the risk of venous thromboembolism was about 23 per 100,000 ‘woman-years’ in users of the drospirenone pill and 9 per 100,000 woman-years in users of levonorgestrel pills,” said Dr Lianne Parkin of the University of Otago’s Department of Preventative and Social Medicine.

Parkin says laboratory tests have shown that drospirenone is a stronger cause of protein C resistance, one aspect of blood clotting, than older pills. She also said there is no clear evidence for greater effectiveness in pregnancy prevention.

Cane Toads Cleared of Parasite claims
Cane toads might be one of Australia’s worst, and ugliest, invasive species but they’re innocent of the accusation that they brought parasites with them.

This is the conclusion of University of Sydney PhD student Ashlie Hartigan, who found that two species of myxosporean parasites are different from their South American equivalents, suggesting they are native rather than having been introduced with the toads, as previously thought.

The parasites affect three species of bell frog, including the yellow spotted bell frog, which is thought to have been extinct for 30 years. “Infected frogs lose weight, are lethargic, and some can’t move their back legs, making them more vulnerable to predators,” Hartigan says.

“We are 99% sure the cane toad did not bring it in,” Hartigan claims. “If we can learn more about the life cycle of these parasites, how they are spread, and identify other potential hosts we will be able to screen frogs for infection and control the spread to captive breeding populations and threatened populations in the wild.”

The work was published in PLoS One.

Pneumonia Risk from Vitamin D Deficiency
Patients with vitamin D deficiency when admitted to hospital for pneumonia were more likely to die within a month than those with normal or near healthy vitamin D levels a study of 112 patients at Waikato Hospital has found.

“As an observational study we were not able to establish causal associations between vitamin D deficiency and mortality in these patients,” said Dr Ray Cursons of Waikato University Biological Sciences.

Evidence for the importance of vitamin D across many aspects of the body, including the immune system, is growing rapidly (AS, December 2010, p. 5) but co-author of a Respirology paper on the research Dr Noel Karalus of Waikato Hospital said supplements on entering hospital may not be the answer. “It may transpire that vitamin D helps us avoid infection rather than cure it once established.”

Drug Consumption Changing
Australians are shifting away from ecstasy as a recreational drug in favour of newer synthetic drugs, according to a report from the National Drug and Alcohol Research Centre at the University of New South Wales.

“The sheer rate at which these and other chemicals could be synthesised and distributed presents significant challenges from a health perspective and a law enforcement perspective,” says Dr Lucy Burns. One of the newer drugs, BZP, is believed to have more side effects than amphetamines.

Former ecstasy users blame declines in the purity of drugs for sale for their change in preference. Analysis of tablets sold as ecstasy in 2008/09 found an average of 22% MDMA, the active ingredient, with some having no MDMA at all. Similar trends have been observed in Europe.

Eat Your Reds
The benefits of lycopene, the red pigment that gives tomatoes their colour, have been extended to preventing cardiovascular disease according to a paper in Maturitas.

Lycopene is an anti-oxidant long suspected of preventing cancer. Now Dr Karin Ried of the University of Adelaide’s Primary Health Care, Research Evaluation and Development Program has conducted a metastudy of 14 papers investigating lycopene’s relationship with a healthy heart. "Our study suggests that if more than 25 milligrams of lycopene is taken daily, it can reduce LDL-cholesterol by up to 10%” says Reid. "That's comparable to the effect of low doses of medication commonly prescribed for people with slightly elevated cholesterol, but without the side effects of these drugs, which can include muscle pain and weakness and nerve damage."

Lycopene also exists in red and pink fruit such as watermelon and guava. However, it’s bioavailability is much higher in when tomatoes have been processed into sauce than when they are fresh (AS, July 2009, p. 10).

Online Pest Identification
Border security field officers will now be able to get instant help identifying insects and other potential pests they come upon while searching for invasive species.

Where once the would have to bring the specimen back to base the Remote Microscope Network allows an officer to show what they are seeing to an expert in real time over the Internet. The field officer and the taxonomist can also discuss the environment in which the suspected pest was located, and relevant questions can be tested immediately.

“We’ve added a new innovative tool to our system which is very cost effective and efficient, and decreased the response time when dealing with potentially harmful pests and diseases,” says Dr Simon McKirdy of the Cooperative Research Centre for National Plant Biosecurity.

Fatigue Measuring Cap
An object that looks and feels like a baseball cap, but monitors the wearer’s level of fatigue could save mining companies millions of dollars in prevented accidents, and eventually slash the road toll.

SmartCap uses unique sensors capable of reading neural signals through hair. The cap reads the brain’s response and displays a measure of tiredness in the cab of the vehicle being operated. The results can also be relayed back to a base station.

CEO of the Mining Cooperative Research Centre Prof Mike Hood says, “The many advantages of the SmartCap include the fact that it is lightweight, mobile and highly accurate at detecting fatigue in drivers,” he says. “This means the technology is easily adaptable to a passenger car environment.”

The Mining CRC estimates the market for SmartCaps in mining operations is almost 10,000 worldwide, but even without reaching ordinary car drivers there is potential to expand to 1.2 million heavy truck operators.

TV Impacts Show Early
Parents who warn their children that too much television is bad for the eyes may be right in a way they don’t realise.

Research published in Arteriosclerosis, Thrombosis and Vascular Biology found that 6-year-olds who watch more TV have narrower arteries in the back of their eyes. This may not affect their eyesight, but adults with narrower retinal arteries have higher blood pressure and are more at risk of heart disease and diabetes.

Dr Bamini Gopinath of the University of Sydney’s Centre for Vision Research acknowledges that no connection between narrowed arteries in the children’s eyes and high blood pressure later in life has been established. However, based on the adult data she suspects that each daily hour of television watching at a young age is equivalent to a 10 mm Hg increase in blood pressure later in life.

On the other hand, Gopinath says that “we found children with a high level of physical activity had a more beneficial microvascular profile compared to those with the lowest levels of physical activity”.

Children who spent more time watching television tended to spend less running around outside, so Gopinath says it was hard to determine whether it was the time in front of a TV or the absence of physical activity, or a combination, that triggered the arterial narrowing. Indoor activity appeared to offer a smaller benefit to similar behaviour outdoors.

Gopinath also looked at the effects of other sedentary behaviour and did not find a similar link to arterial narrowing, but thinks this may be because 6-year-olds are not playing enough computer games to create problems. She is interested in conducting the same research with older children.

Retinal arteries can be measured simply by taking a photograph of the eye and having a computer check the width of the arteries.

Galaxy Defined by Popular Vote
The people have voted, and a galaxy is defined. Prof Duncan Forbes of Swinburne University is attempting to head off a repetition of the negative public response to the demotion of Pluto by asking the public to comment on proposals that would differentiate small galaxies from large globular clusters.

Forbes co-wrote a paper setting out five possible measures, and ran an online poll to gauge interest (AS, May 2011 p. 8). With 1600 votes the verdict was clear: 68% indicated that a galaxy needs to have complex stellar populations with a range of ages and chemical properties.

The definition is effective, since globular clusters are characterised by highly homogonous stars, but it is perhaps surprising that definitions based on size, stellar motion, satellites and the presence of dark matter were so far behind. In particular the choice of population complexity over size suggests that most voters assessed the criteria’s merits rather than choosing the most obvious.

This definition makes Omega Centauri a galaxy, a matter of some debate (AS, Nov/Dec 2003 p. 9). Voting remains open at www.surveymonkey.com/s/wlrjmws.