Science: In brief

House dust, shown under magnification, may contain allergens and bacteria.
PHOTO: Science: In brief

Allergen exposure may help kids

You really can be too clean. Children who are exposed to specific allergens and bacteria within their first year may be protected from wheezing and allergic diseases, according to research funded by the United States National Institutes of Health (NIH). Recurrent wheezing and sensitivity to common allergens are risk factors for developing asthma in a young child.

In the study, researchers measured the frequency of wheezing episodes and levels of exposure to five common inner-city allergens: cat, cockroach, dog, dust mite and mouse.

They found that exposure to cockroach, mouse and cat during the first year of life was associated with a lower risk of recurrent wheezing by age three.

A smaller study also tested whether bacteria, measured in house dust, influenced asthma risk.

It found that children with no wheezing or sensitivity to allergens at age three were more likely to have encountered high levels of allergens and a greater variety of bacteria during their first year of life.

These observations support the emerging concept that early-life exposure to high bacterial diversity may protect children from developing allergies, and that this protection is even stronger when children also encounter high allergen levels during this time, said the NIH.

6,000 steps to healthier knees

People who walk 6,000 or more steps each day are less likely to develop mobility problems from knee osteoarthritis, such as difficulty getting up from a chair or climbing stairs.

Knee osteoarthritis is a chronic and debilitating degeneration of the knee joint.

For the study, researchers measured daily steps taken by 1,788 people with or at risk of the condition.

They found that walking an additional 1,000 steps each was associated with a 16 per cent to 18 per cent reduction in functional limitation two years later.

Walking fewer than 6,000 steps daily was the best threshold for identifying those who developed functional limitation, such as difficulty walking and climbing stairs.

Said Dr Daniel White of Sargent College at Boston University in Massachusetts: "Walking is an inexpensive activity and, despite the common popular goal of walking 10,000 steps per day, our study finds only 6,000 steps are necessary to realise benefits.

"We encourage those with or at risk of knee OA to walk at least 3,000 or more steps each day, and ultimately progress to 6,000 steps daily to minimise the risk of developing difficulty with mobility."

GM mosquitoes to battle malaria

Scientists have modified mosquitoes to produce sperm that will create only males, pioneering a fresh approach to eradicating malaria.

Scientists from Imperial College London tested a new genetic method that distorts the sex ratio of Anopheles gambiae mosquitoes, the main transmitters of the malaria parasite, so that the female mosquitoes that bite and pass the disease to humans are no longer produced.

In the first laboratory tests, the method created a fully fertile mosquito strain that produced 95 per cent male offspring.

The scientists introduced the genetically modified mosquitoes to five caged wild-type mosquito populations. In four of the five cages, this eliminated the entire population within six generations because there were no females.

The hope is that if this could be replicated in the wild, this would ultimately cause the malaria-carrying mosquito population to crash.

This is the first time that scientists have been able to manipulate the sex ratios of mosquito populations, said Imperial College London in a statement.

Compiled by Chang Ai-Lien

This article was first published on June 15, 2014.
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