Scientists on Sunday said they had found a key piece in the puzzle as to why a tiny minority of individuals infected with HIV have a natural ability to fight off the deadly AIDS virus.

In a study they said holds promise for an HIV vaccine, researchers from four countries reported the secret lies not in the number of infection-killing cells a person has, but in how well they work.

European and Australian scientists on Sunday said they had snared four more genes that highlight an inherited cause for common migraine.

The genetic variants were spotted in a trawl through the DNA code of 4,800 people with a history of "migraine without aura," which accounts for two-thirds of migraine attacks.

People who survive cancer when they are teenagers or young adults are more likely than their peers who never had cancer to engage in risky behaviors like smoking later on, a U.S. study said Monday.

They also are more likely to be overweight and have mental health issues and financial problems than their cancer-free counterparts, said the research in the journal Cancer, a peer-reviewed publication of the American Cancer Society.

The Canadian province of Quebec announced Friday that it is suing tobacco giants for more than $60 billion dollars in a bid to recover health care costs associated with smoking-related illnesses.

The lawsuit targets the Canadian tobacco companies and their parent companies abroad and seeks damages related to the cost of treating patients from the 1970s until 2030, Quebec Justice Minister Jean-Marc Fourner said.

People with cancer who were caught in the aftermath of the World Trade Center collapse during the September 11, 2001 terrorist attacks on New York should be eligible for aid, authorities proposed Friday.

A wide range of dozens of cancers was recommended to be added to the list of conditions officially linked to 9/11, when thousands of local residents and rescue workers were forced for weeks to breathe dust and fumes from the fallen towers.

A woman reported to be visiting Australia from China has died after eating a toxic Death Cap mushroom -- the third such fatality in the southern nation this year.

The woman, aged in her 50s, died Friday at the Austin Hospital in Melbourne, two days after being admitted with severe poisoning due to ingestion of the fungi, which resembles the Paddy Straw mushroom, a popular delicacy in Asia.

A vaccine which revives a promising but long-abandoned path to thwart Alzheimer's disease has cleared a key safety hurdle in human trials, researchers say.

In a small-scale test, the formula was found to be safe and primed the body's frontline defenses against protein deposits in the brain that are associated with the catastrophic disease.

Pneumonia and diarrhea are among the top causes of childhood deaths around the world, particularly among the poor, said a report out Friday by the U.N. Children's Fund.

UNICEF said that while these two diseases kill more than two million children each year, making up 29 percent of child deaths under age five worldwide, some simple interventions could save lots of lives in the coming years.

Japanese researchers have created a functioning human liver from stem cells, a report said Friday, raising hopes for the manufacture of artificial organs for those in need of transplants.

A team of scientists transplanted induced pluripotent stem (iPS) cells into the body of a mouse, where it grew into a small, but working, human liver, the Yomiuri Shimbun said.

Scores of Taiwanese activists staged a protest in Taipei on Friday against U.S. beef containing the feed additive ractopamine ahead of a parliamentary vote on a controversial bill to allow such imports.

"American bullies, toxic beef," the protesters shouted, waving matching placards as they rallied outside the de facto U.S. embassy in Taipei.