Why do birds sing? It's all in the brain

Birds start singing in the spring because of a biological response to longer days, researchers said on Wednesday.

When birds are exposed to light for longer periods, certain brain cells trigger a series of hormonal reactions telling them to find a mating partner, which they do by singing, a team of Japanese and British researchers reported in the journal Nature.

"While we knew what area of the brain was affected by seasonal change, until now we did not know the exact mechanism involved," said Peter Sharp, a researcher at the Roslin Institute near Edinburgh, who worked on the study.

The researchers, led by Takashi Yoshimura of the Nagoya University in Japan, scanned 38,000 genes present in brain samples taken from Japanese quails to see which of the birds' genes were affected by varying degrees of light.

Genes in cells on the surface of the brain switched on when the birds received more light and began releasing a thyroid-stimulating hormone.

The genes activated 14 hours after dawn on the first day of sufficient length, the researchers said.

"Such knowledge would have been impossible in the past, but advances in technology enabled us to scan thousands of genes so that we could work out which ones are affected by seasonal change," Sharp said in a telephone interview.

This hormone, previously associated with growth and metabolism, helped to stimulate the pituitary gland to secrete other hormones. In turn this caused the birds' testes to grow, which eventually resulted in crowing to attract a mate.

The findings could also one day lead to better treatments for infertility because humans have the same cells in the same part of the brain, Sharp added.

"It is sitting there and standing there with the same characteristics as in birds," he said. "The big question is whether these cells are involved in the reproductive system."

Study sheds light on paralysing nerve condition

British researchers have discovered a genetic mutation that causes a paralysing illness called ALS in some people, a finding they said on Thursday may lead to treatments for the degenerative nerve condition.

Their study showed how this genetic variation produced proteins that were toxic and killed motor neuron cells in people with amyotrophic lateral sclerosis or ALS, also commonly known as motor neuron disease or Lou Gehrig's disease.

"We discovered that the mutation was appearing only in people who were affected," said Chris Shaw, a researcher at the Institute of Psychiatry in London who led the study published in the journal Science. "This suggested it is disease-causing."

The finding is important, he said, because the disease kills quickly -- usually between two and five years after symptoms start -- and has no effective treatments. Physicist Stephen Hawking is a rare example of a person who has survived for years with the condition.

ALS leaves people unable to walk, talk or feed themselves but does not usually affect their intellect and other senses. Doctors diagnose about 120,000 new cases each year, according to the International Alliance of ALS.

Shaw and colleagues isolated a mutation in a gene called TARDBP in people with a rare, inherited form of ALS. They found that people with this variation produced a mutant and toxic protein called TDP-43.

Previous research had suggested the protein might have existed as sort of cellular junk generated as a harmless by-product of the disease. But by injecting these mutated proteins into the spines of chicks in eggs, Shaw's team showed they actually killed motor neurons.

While only about 1 percent of people have this form of ALS, the findings have wider implications because most people with the disease have these proteins accumulating in the wrong place within the cell, Shaw said.

"It also means we develop new and better disease models, which will bring us close to developing more effective therapies," he said.

In 1993 a group of U.S. researches identified a gene called SOD1 that caused a form of ALS affecting about 5 percent of people with the disease -- the only people with the condition who do not accumulate TDP-43 proteins, Shaw said.

That finding triggered a flood of new research into the disease, and the discovery of a second gene could draw even more people into the field, said Brian Dickie, director of Research Development at Britain's Motor Neuron Disease Association.

"The discovery of a new cause of the disease is of international importance, allowing researchers around the world to rapidly generate more pieces of the complex puzzle that is motor neuron disease," he said.

Airport noise instantly boosts blood pressure

Living near an airport isn't just irritating, it is also unhealthy, researchers said on Wednesday, in a study that showed loud noise instantly boosts a sleeping person's blood pressure.

The louder the noise, the higher a person's blood pressure went, a finding that suggests people who live near airports may have a greater risk of health problems, said Lars Jarup, who led the European Commission-funded study.

"Living near airports where you have exposure to night time aircraft noise is a major issue," Jarup, an environmental health researcher at the University of Glasgow, told Reuters.

"The reason we did airports is because there was no study that has looked at particular problems of aircraft noise."

High blood pressure can lead to stroke, heart failure, heart attack and kidney failure. It affects more than a billion adults worldwide.

The research team showed that people living for at least five years near a busy airport and under a flight path have a greater risk of developing chronic high blood pressure, also known as hypertension, than those who live in quieter areas.

That study of nearly 5,000 people found that an increase in night time airplane noise of 10 decibels increased the risk of high blood pressure by 14 percent in both men and women.

"We know that noise from air traffic can be a source of irritation, but our research shows that it can also be damaging for people's health, which is particularly significant in light of plans to expand international airports," Jarup said.

In the four-year study, published in the European Heart Journal, the researchers remotely measured the blood pressure of 140 volunteers every 15 minutes while they slept in their homes near London's Heathrow airport -- one of the busiest in the world -- and three other major European airports.

They used digital recorders to determine what noises had the biggest impact on blood pressure, ranging from road traffic to a partner's snoring to an airplane taking off or landing.

The Decibel level, not a sound's origin, was the key factor, but airplanes had the most significant impact, Jarup said.

"Most of the time you will find road traffic noise is not too bad during the night," he said. "If you live near an airport where there are night flights, that is quite another story."

Heart attacks drop after Italy's smoking ban

Italy's 2005 smoking ban has led to a sharp fall in heart attacks, researchers reported on Monday in a finding they said shows that such laws really do improve public health.

Following the ban the number of heart attacks in men and women aged 35-64 -- people most likely to be exposed to smoke in cafes, bars and restaurants -- fell 11 percent, the researchers said.

The findings showed the health benefits of European smoking bans in public places, said Francesco Forastiere, an epidemiologist at the Rome Health Authority who led the study.

"Most of this change is due to the decreased impact of passive smoke," he said in a telephone interview. "This is ... important because it shows the impact of a health intervention that can be achieved in other countries."

Italy, Britain, Ireland and a number of other European countries have outlawed smoking in public places, and many health experts are urging the European Union to adopt an even wider ban.

The ban in Italy, where the researchers said about 30 percent of men and 20 percent of women smoke, prohibited smoking cigarettes in all indoor public places such as offices, retail shops, restaurants, pubs and discos.

STRONGLY ENFORCED

"Smoking bans should be extended to all possible countries and smoking bans in the workplace should be strongly enforced," the researchers wrote.

Writing in the American Heart Association journal Circulation, the researchers compared the rate of heart attacks from 2000 to 2004 to those occurring in the year after the ban was enforced.

The team analyzed hospital records and adjusted for heat waves, flu epidemics, air pollution and other factors that could have contributed to heart attacks. The researchers also took daily measurements on air quality in 40 public places.

"The smoking ban in Italy is working and having a real protective effect on population health," Forastiere said.

After the ban, cigarette sales also fell 5.5 percent but the researchers attributed the health benefits seen in the study to reduced exposure to passive smoke.

They said young men and women living in poorer areas appeared to have the greatest health benefit after the ban.

Smoking kills about four million people each year while about a quarter of deaths related to heart disease are due to cigarettes, according to the World Health Organisation.