In brief– Research news and discovery

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POINTERS to possible drug treatments for multiple sclerosis have come from an experiment in which extra doses of a natural hormone relieved symptoms of the disease in mice.

In MS, the immune system attacks and destroys the fatty myelin sheath around nerve cells, causing physical and cognitive disability. Myelin is produced by cells called oligodendrocytes,

whose development is controlled by the hormone triiodothyronine, which is made in the thyroid .

To see if extra doses of this hormone might help to “remyelinate” nerves, Said Ghandour at the Louis Pasteur University in Strasbourg, France, and colleagues gave mice a chemical that destroys myelin, causing a mouse version of MS. The mice had seizures and lost

the ability to coordinate their movements. When the mice then received injections of the thyroid hormone for three weeks, these symptoms improved (The Journal of Neuroscience, DOI: 10.1523/JNEUROSCI.4453-08.2008 ).

In people, an overactive thyroid can cause nervousness, heart palpitations and weight loss. As Ghandour fears extra doses of the hormone might do the same, he suggests creating drugs to mimic the hormone’s effect on the brain but not the rest of the body.

Thyroid hormone repairs MS damage

THE brightness of white dwarfs may point towards the existence of exotic dark matter particles.

Jordi Isern of the Institute of Space Sciences in Bellaterra, Spain, and colleagues modelled what would happen if white dwarfs – small, dense, dying stars – were emitting axions. These hypothetical particles are a candidate for dark matter, which makes up most of the universe.

The model showed that axion emission affected a white dwarf’s brightness, and the distribution of stars of a given luminosity predicted by the model matched well with observations of 6000 white dwarfs by the Sloan Digital Sky Survey ( www.arxiv.org/abs/0812.3043 ). This is the first indication that axions could exist, say the team .

Right stuff for the dark stuff

WHAT controls a beating heart? It seems the life-giving mechanism is simpler than we thought.

Each beat is triggered by a surge of calcium ions that causes millions of overlapping filaments in a heart cell to pull against each other and contract. These filaments are made of two proteins called actin and myosin.

Actin must be “activated” before contraction can occur and it was thought that both calcium and myosin were necessary for this step. But when Yin-Biao Sun at King’s College London and colleagues , funded by the British Heart Foundation, attached fluorescent probes to rat versions of the proteins, calcium ions alone seemed to activate actin (The Journal of Physiology, DOI: 10.1113/jphysiol.2008.164707).

A persistent abnormal heart beat causes many heart problems, so a better understanding of how healthy beating is controlled may aid new drug development.

Beat generation

WHEN you’re in love, everything seems different – and that includes smells. Compared with their less besotted counterparts, women who are madly in love struggle to recognise the body odours of male friends.

So say Johan Lundström and Marilyn Jones-Gotman of McGill University in Montreal, Canada. They asked 20 young women with boyfriends to fill in a questionnaire called the Passionate Love Scale to rate how deeply in love they were. They also persuaded the women’s partners and male and female friends to sleep for seven nights in a cotton T-shirt.

The women were asked to sniff the shirts to distinguish those worn by their lovers and friends from those of strangers. The more deeply in love a woman was, the less well she did at distinguishing a male friend’s odour from those of strangers. When it came to recognising the odours of male lovers or female friends, however, the women’s love score was unrelated to how well they did (Hormones

and Behavior, DOI: 10.1016/j.yhbeh.2008.11.009).This suggests a lover doesn’t pay more attention to her

partner – just less to potential suitors. “I’m not really a love guru,” protests Lundström, now at the Monell Chemical Senses Center in Philadelphia, Pennsylvania. His next project will investigate what happens in lovers’ brains as they perceive the odours of partners, friends and strangers.

Other men all smell the same if a boyfriend’s on the scene

12 | NewScientist | 10 January 2009 www.newscientist.com