Australasian Science Magazine

By Stephen Luntz

Brief bites of science news

Simple Snoring No Threat
Seagrass Beds Recover
Falls Can Be Prevented
Hens Need Nest Boxes
Don’t Mix Drinks
Vitamin D No Cold Protection
Electrode Sheets Analyse Stomach
Faba Beans Against Cancer
Low Allergy Milk
Wasp Hunts Redback Spiders
Dark Matter Illuminated by Prime Minister’s Prize

Snoring that is not accompanied by sleep apnoea does not raise the risk of cardiovascular disease, researchers at the Woolcock Institute of Medical Research have concluded.

Dr Nathaniel Marshall looked at the health outcomes of 380 people who were tested for sleep apnoea and snoring in 1990. Unlike many studies that rely on self-reporting, this one used monitoring devices. In the following 17 years those who snored, but did not suffer sleep apnoea, were no more likely to die or suffer cardiovascular disease.

“We do know already from this study that sleep apnoea increases cardiovascular disease risk,” Marshall said. “Some of our colleagues are also looking closely to see whether snoring by itself might increase stroke risk in people who are highly susceptible. However, the good news at the moment seems to be that snoring, by itself, does not seem to appreciably increase cardiovascular disease or death rates.”

The impact on the health of sleeping partners was not recorded.

The seagrass beds of Moreton Bay made a swift recovery from the 2011 Brisbane floods. A million tonnes of sediment and pollutants were dumped on the beds as a result of that year’s enormous floods, and Dr Russ Babcock of CSIRO Marine and Atmospheric Research told the Coast to Coast conference: “Seagrass cover in Moreton Bay declined by half shortly after the floods.”

However, while corals are struggling to recover from earlier cyclone events, Babcock added: “It was great to see the beds recover to pre-flood levels less than 12 months later”.

CSIRO documented the flood’s effects using remote sensing and underwater robot gliders. They observed damage from the Brisbane River’s flood plume as far north as Fraser Island.

The recovery was both heartening and surprising because some seagrass beds have not recovered from damage suffered from floods in the 1990s.

A review of 159 trials with 79,000 participants has revealed the interventions that provide the most benefit in avoiding falls among people over the age of 65 who live in their own homes.

“Falls have debilitating and isolating social consequences for older people, not to mention the increasing economic cost they present in our ageing population,” says Prof Lindy Clemson of the University of Sydney’s Faculty of Health Sciences.

The Cochrane review of trials conducted in Australia, New Zealand and the UK found benefits for certain changes to medication, and even from the fitting of pacemakers for particular heart disorders. Cataract surgery on one eye was also helpful, although there was no further benefit from surgery on the other eye.

More simple interventions such as anti-slip shoe coverings for icy conditions and exercises could also reduce the 30% of over-65s in the community who are currently affected by falls.

The provision of darkened nest boxes is an important factor in hen happiness, according to Dr Greg Cronin of the University of Sydney. Cronin tested levels of the stress hormone corticosterone on 112 hens, half of which had access to nest boxes.

All the hens were kept in cages, but the corticosterone levels of those with boxes was lower than those forced to lay eggs in the light. “They want to find a spot where they’re protected and safe so their eggs have got the most chance of hatching and therefore they can reproduce,” said Cronin. “The birds that are the most relaxed are the ones that can sit for longer.”

While the work marks a step towards more objective testing of hen welfare, not all scientists accept corticosterone as a reliable measure of avian mental health, and 29% of birds with access to nest boxes did not use them.

Young Victorians mixing energy drinks with alcohol are unaware of the risks involved, a study by the Turning Point Alcohol Centre has found. “Energy drinks are concentrated with stimulants like caffeine, ginseng and taurine, while alcohol is a depressant. By mixing the two it confuses the nervous system, which can often trigger cardiac problems,” said Dr Amy Pennay.

While most of the 18–35-year-olds surveyed for Pennay’s study, published in Biomedcentral, listed trouble sleeping as the main negative from energy drinks, she said potential symptoms of overstimulation include “severe hangovers, aggression, violence, heart palpitations, blackouts, vomiting and tremors”. Combining the drinks with alcohol, as is increasingly popular as a way of keeping alert on a big night out, magnifies these risks.

Vitamin D pills do not protect against colds, according to a study published in the Journal of the American Medical Association.

Evidence for the beneficial effects of Vitamin D is mounting in many areas (AS, October 2012, p.13), and supplements are increasingly popular as protection against the common cold. However, an 18-month study of 300 residents of Canterbury found those given a placebo rather than a vitamin D pill were no more likely to get sick, and did not suffer more serious colds when they did.

Prof David Murdoch of the University of Canterbury cautioned: “It is important to note that very few people in our study had extremely low levels of vitamin D at the beginning. So, our findings may not apply to these people and to children, who should now be the focus of further research.’’

The University of Auckland has used sheets of hundreds of electrodes to track electrical patterns in the stomach during surgery for gastroparesis, and developed a software program to process the patterns produced.

“Gastroparesis is a devastating disease that is particularly difficult to diagnose and treat, and its causes have been poorly understood,” said Dr Gregory O’Grady of the University of Auckland. The stomachs of sufferers are unable to empty themselves normally, leading to chronic nausea, vomiting and abdominal pain. The condition affects 10% of diabetics.

“Previous research had been impeded due to there being no adequate methods to investigate gastric electrical activity. Our research provides significant new insights into the disease, and opens the door to advanced new treatment options such as the use of gastric pacemakers.”

Faba beans have been found to contain chemicals that induce normal cell death in cancer cells in vitro. Charles Sturt University PhD student Siem Siah introduced phenolic compounds from faba beans to bladder, stomach, liver and colon cancer cell lines. All showed increased death rates.

Phenolic compounds are antioxidants that provide plants with colour, metabolism and defence against parasites. “We know that antioxidant properties are potentially linked to anti-cancer properties, so we were trying to look for the connections,” said Siah.

Siah’s work was published in the British Journal of Nutrition, and is in addition to evidence that faba bean extracts inhibit angiotensin-converting enzyme (ACE), high levels of which are associated with cardiovascular disease.

A calf has been genetically engineered so that does not produce one of the major causes of allergies to cow’s milk. “Two to three percent of infants are allergic to cow’s milk, and BLG allergies make up a large part of that percentage,” says Dr Stefan Wagner of New Zealand’s AgResearch.

Wagner’s team first engineered mice to produce the protein beta-lactoglobulin (BLG). They then used RNA interference to knock down the expression of the BLG protein, producing a 96% reduction. The same two microRNAs were then engineered into a calf named Daisy. When Daisy lactated, BLG proteins were below detectable levels.

“People have long looked into reducing this enigmatic protein, or completely knocking it out, because there has been no definitive function able to be assigned to it,” says Wagner.

Lactation was induced hormonally to speed up the process, but Wagner is now planning to breed Daisy to test natural lactation.

Wasp Hunts Redback Spiders

A 9-year-old child has found that a wasp collected during Captain Cook’s first voyage preys on redback spiders. Florian Irwin saw a wasp dragging a paralysed redback to its nest and alerted his father. An academic in veterinary sciences, Dr Peter Irwin photographed the event and informed entomologists.

Prof Andy Austin of Adelaide University’s Centre for Evolutionary Biology and Biodiversity says the wasp Agenioideus nigricornis is “widespread across Australia and can be found in a number of collections, but until now we haven’t known the importance of this particular species”.

“We’re very excited by this discovery, which has prompted us to study this species of wasp more closely. It’s the first record of a wasp preying on redback spiders (Latrodectus hasselti), and it contributes greatly to our understanding of how these wasps behave in Australia,” Austin says. The wasp lays its eggs in the paralysed spider so the larvae can feed upon it.

Professor Ken Freeman, the Duffield Professor of Astronomy at the Australian National University’s Mt Stromlo Observatory, has been awarded the 2012 Prime Minister’s Prize for Science.

Freeman is best known for putting “dark matter” on the galactic map after showing in 1970 that what we see of galaxies is only a small fraction of their mass while the rest is dark matter. His finding changed the course of astronomy.

More recently Freeman has been a founder of galactic archaeology – determining the age and movement of stars in our own galaxy by analysing their chemical composition. The aim is to work out how galaxies were constructed, and the field has become a major driver in the commissioning of new ground- and space-based telescopes.

Dr Mark Shackleton of the Peter MacCallum Cancer Centre was awarded the 2012 Science Minister’s Prize for Life Scientist of the Year for melanoma research. Shackleton has found that at least one in four melanoma cells – not one in a million as previously thought – can produce cancerous offspring. This completely overturned the idea that cancer growth is fuelled by rare cancer stem cells, and means that doctors will effectively need to eliminate all cells in order to offer the hope of a cure.

Professor Eric May of the University of Western Australia was awarded the 2012 Malcolm McIntosh Prize for Physical Scientist of the Year for research into the fundamental fluid properties of liquid natural gas. His work is ensuring the smooth flow of gas from well to production facility and its efficient conversion to a safe and usable product that can be traded internationally and easily delivered to customers.