People who are usually happy and enthusiastic are less likely to develop heart disease than those who tend to be glum, scientists said on Thursday, and boosting positive emotions could help cut heart health risks.

US researchers said their observational study was the first to show an independent relationship between positive emotions and coronary heart disease, but stressed that more work was needed before any treatment recommendations could be made.

Trying to quit smoking? So-called nicotine-free cigarettes may be as helpful as nicotine lozenges, hints a small study.

Smokers who used the nicotine-free cigarettes before quitting were as likely not to be smoking six weeks later as those who used nicotine lozenges, authors report in the journal Addiction. (Such cigarettes actually have a tiny amount of nicotine.)

Old tobacco smoke does more than simply make a room smell stale -- it can leave cancer-causing toxins behind, US researchers reported on Monday.

They found cancer-causing agents called tobacco-specific nitrosamines stick to a variety of surfaces, where they can get into dust or be picked up on the fingers.

Scientists say they have solved a crucial puzzle about the AIDS virus after 20 years of research and that their findings could lead to better treatments for HIV.

British and U.S. researchers said they had grown a crystal that enabled them to see the structure of an enzyme called integrase, which is found in retroviruses like HIV and is a target for some of the newest HIV medicines.

The H1N1 flu pandemic appears to be easing, but a third wave of infections could yet strike, the World Health Organisation (WHO) said on Monday.

"Pandemic infections are occurring in many countries but overall the pattern is decreasing," Keiji Fukuda, the WHO's top flu expert, said at the start of a week-long meeting of the organisation's Executive Board.

More than three percent of sudden deaths in Europe are related to cocaine use and many of them are brought on by a "lethal cocktail" of the drug, alcohol and cigarettes, scientists said on Wednesday.

Results of a study on sudden death show there is no such thing as safe recreational cocaine use, the researchers said, and suggest the 12 million Europeans who use cocaine are putting their lives on the line.

If you needed another reason to cut the cigarette habit: Smokers, especially younger smokers, are more likely to report low back pain than people who have never smoked, according to a new analysis.

After examining existing research, Finnish researchers concluded smoking is "modestly" associated with the risk of low back pain and the effects may be "at least partly reversible." Their findings are published in the January issue of the American Journal of Medicine.

The head of the World Health Organisation (WHO) has finally been vaccinated against H1N1 flu, a virus expected to infect more people in coming months, the UN agency said on Tuesday.

Margaret Chan, WHO director-general, was vaccinated on Dec. 30, a day after admitting at a news conference that she had not got round to it due to travel and other demands.

A new study confirms that smoking raises a person's risks of the major forms of esophageal and stomach cancers, while drinking has more narrow effects.

In a study that followed more than 120,000 Dutch adults for 16 years, researchers found that smoking increased the risk of the two main forms of stomach cancer, as well as the two forms of esophageal cancer -- by anywhere from 60 percent to 263 percent versus non-smokers.

If you recently tweeted about how you were chillaxin for the holiday, take note: Fifteen particularly over- or mis-used words and phrases have been declared "shovel-ready" to be "unfriended" by a US university's annual list of terms that deserve to be banned.

After thousands of nominations of words and phrases commonly used in marketing, media, technology and elsewhere, wordsmiths at Lake Superior State University on Thursday issued their 35th annual list of words that they believe should be banned.

Perhaps it's not surprising, but for members of the US armed forces, combat duty in Iraq and Afghanistan increases the risk of depression, according to a new study.

Timothy S. Wells of the US Air Force Research Laboratory, Wright-Patterson Air Force Base in Ohio, studied more than 40,000 members of the US military who had been free of symptoms of depression and had not taken medication for anxiety, stress, or depression before deployment.

At least 11,516 people around the globe have died from the H1N1 flu virus since the pandemic emerged in April, the World Health Organisation (WHO) reported on Wednesday.

But in its weekly update, which showed an increase in officially reported deaths of nearly 1,000 since its last report, it said the disease appeared to have peaked or plateaued in Western Europe and North America while transmission was declining in parts of Asia.

Autism, a brain disorder that interferes with communication and social skills, affected an estimated one in 110 American 8-year-olds in 2006, according to a federal study released Friday.

The US Centers for Disease Control and Prevention looked at the medical diagnoses of 307,790 children who were age 8 in 2006. They found 2,757, or 0.9 percent, had been diagnosed with autism.

Coffee, tea, or decaf-no matter what your choice, drinking any of these beverages may reduce your risk of diabetes, according to a new analysis of 18 studies including hundreds of thousands of people.

A 2005 research review concluded that people who drank the most coffee were one-third less likely to develop diabetes than those who drank the least, Dr. Rachel Huxley of The University of Sydney, Australia, and colleagues note.

More than 94 percent of the world's people are not protected by laws against smoking, leaving them exposed to the biggest cause of preventable death, the World Health Organisation said on Wednesday.

In a Global Tobacco Epidemic report the WHO said smoke-free policies were crucial to reducing the harm caused by second-hand smoke, which it said kills around 600,000 people prematurely each year and causes crippling, disfiguring illness and economic losses reaching tens of billions of dollars.

The second storey of this nondescript building in Fuyang city in China's central province of Anhui houses HIV-positive orphans, but unlike many other similar establishments, there are no signboards outside.

Heavy stigma still surrounds the disease in China, and children -- probably the most vulnerable group among AIDS patients -- are almost invariably barred from schools and even abandoned by their parents and relatives.

The guns are gradually falling silent in Iraq as a fragile stability takes hold, turning the spotlight on a stealthier killer likely to stalk Iraqis for years to come.

Incidences of cancer, deformed babies and other health problems have risen sharply, Iraqi officials say, and many suspect contamination from weapons used in years of war and accompanying unchecked pollution as a cause.

Democrats in the US Senate geared up for a fierce battle over a new healthcare reform plan on Thursday as Republicans condemned the bill's price tag and tax hikes before the first crucial test vote on Saturday.

Senate Democratic leader Harry Reid's 2,074-page blueprint for overhauling the $2.5 trillion healthcare system sparked what promises to be a long and bitter debate over President Barack Obama's top domestic priority.

Australian surgeons have separated Bangladeshi conjoined twins Krishna and Trishna in a marathon operation at a hospital in Melbourne.

After more than 27 hours of surgery that began at 8:30am local time on Monday, plastic surgeons at the Royal Children's Hospital have separated the Bangladeshi girls, aged two years and 11 months.

The US healthcare system is just as wasteful as President Barack Obama says it is, and proposed reforms could be paid for by fixing some of the most obvious inefficiencies, preventing mistakes and fighting fraud, according to a Thomson Reuters report released on Monday.

The US healthcare system wastes between $505 billion and $850 billion every year, the report from Robert Kelley, vice president of healthcare analytics at Thomson Reuters, found.