Twin 2-year-old girls who were joined at the chest and abdomen were separated Tuesday during a lengthy, complex procedure at Stanford University's children's hospital.

The operation that gave Philippines-born sisters Angelina and Angelica Sabuco their independence took more than nine hours and a team of more than 40 people.

Scientists said Tuesday they had transformed age-worn cells in people over 90 -- including a centenarian -- into rejuvenated stemcells that were "indistinguishable" from those found in embryos.

The technical feat, reported in the peer-reviewed journal Genes & Development, opens a new path toward regenerative medicine, especially for the elderly, the researchers said.

People who took yoga classes for chronic lower back pain experienced more lifestyle improvements and better overall health than those who sought a doctor's advice, said a study published Monday.

The research in the U.S. journal the Annals of Internal Medicine was led by scientists at the University of York, included more than 300 people and was described as the largest of its kind to date in the United Kingdom.

Scientists at a Chinese university said Monday they can use rice to make albumin, a protein found in human blood that is often used for treating burns, traumatic shock and liver disease.

When extracted from rice seeds, the protein is "physically and chemically equivalent to blood-derived human serum albumin (HSA)," said the research in the U.S.-published Proceedings of the National Academy of Sciences.

A new study suggests that when parents are deployed in the military, their children are more than twice as likely to carry a weapon, join a gang or be involved in fights.

And that includes the daughters.

Commonwealth government leaders meeting in Australia agreed Saturday to step up efforts to eradicate polio worldwide, despite the Afghanistan war setting back vaccination efforts there and in neighboring Pakistan.

Leaders of Britain, Canada, Australia and Nigeria, as well as billionaire philanthropist Bill Gates, committed tens of millions of dollars in additional funding toward the World Health Organization's campaign to wipe out the disabling disease from the four countries where it remains endemic — India, Afghanistan, Pakistan and Nigeria.

Snakes get a bad rap for being slimy, cold-hearted creatures, but U.S. researchers said Thursday some actually have huge hearts that could offer clues to treating people with cardiac disease.

The secret to the giant Burmese python's success is in a massive amount of fatty acids that circulate in the snake's blood after eating a meal, which could be as big as a deer, according to the study in the journal Science.

Long-term, daily doses of aspirin led to a fall of some 60 percent in cases of colorectal cancer among people with an inherited risk of this disease, the journal The Lancet reported on Friday.

The trial -- considered to be broad in sample and long in duration -- confirms evidence elsewhere that aspirin has a protective effect against cancer of the colon and rectum, it said.

People who received chest X-rays to screen for lung cancer showed no better survival rate after four years than those who were not screened at all, said a U.S. study released Wednesday.

The research, published in the November 2 issue of the Journal of the American Medical Association (JAMA), follows a separate study last year that showed X-rays fell short compared to modern CT scans in saving lives from lung cancer, the leading cancer killer worldwide.

An independent review into breast cancer screening has been launched amid concerns that the diagnostic process could be more harmful than beneficial.

Last month researchers from the Nordic Cochrane Centre in Denmark claimed women given mammograms were being "misinformed" and not told about the risk of over diagnosis.