About half of all 16- to 18-year-olds coming into New York City's jails say they had a traumatic brain injury before being incarcerated, most caused by assaults, according to a new study that's the latest in a growing body of research documenting head trauma among young offenders.

Experts say the findings, published this week in The Journal of Adolescent Health, could lead to better training for correction officers on how to deal with the possible symptoms of such trauma, which include problems with impulse control and decision-making.

For the first time, U.S. researchers have cloned embryonic stem cells from adult cells, a breakthrough on the path towards helping doctors treat a host of diseases.

The embryonic stem cells -- which were created by fusing an adult skin cell with an egg cell that had been stripped of genetic material -- were genetically identical to the donors.

The Philippines said Saturday it was stepping up its defenses against the deadly MERS virus, with the large numbers of Filipino workers in the Middle East seen as potential carriers.

"It is important that families, friends and members of their local communities fully understand all that must be known about the MERS coronavirus," Health Secretary Enrique Ona told a news conference.

A foreigner has died after she contracted MERS in the Saudi capital, the health ministry said on announced Friday, bringing the nationwide death toll to 73.

The 55-year-old woman, whose nationality was not disclosed, was suffering from chronic illnesses, a statement said.

The virus that has caused a deadly Ebola epidemic in Guinea is a new strain that emerged locally, possibly transmitted by fruit bats, virologists have said.

The outbreak is the first to be recorded in west Africa, but researchers said the virus causing it did not come from other countries where Ebola already circulates.

Europe's medicine watchdog urged doctors Thursday to be vigilant in administering the cancer drug Herceptin, vials of which had been stolen in Italy and tampered with before being sold back into the supply chain.

Vials of the drug had been stolen from Italian hospitals in several incidents since last December, and some were tampered with before being resold to wholesalers, said the European Medicines Agency.

Rape victims in Germany are finding it increasingly difficult to see their assailants convicted, a national study released Thursday showed.

Twenty years ago, the percentage of reported sexual violence cases leading to a guilty verdict and sentencing was at about one in five.

Eight million people have signed up for health care through new insurance exchanges and the proportion of younger applicants has increased, President Barack Obama said Thursday. The enrollments exceeded expectations and offered new hope to Democrats who are defending the law ahead of the midterm elections.

An impromptu appearance in the White House briefing room offered the president an opportunity to trumpet the new figures, which beat initial projections by 1 million. With an eye toward November, Obama castigated Republicans for continuing to seek out every opportunity to thwart the Affordable Care Act.

The Ebola virus that has killed scores of people in Guinea this year is a new strain — evidence that the disease did not spread there from outbreaks in some other African nations, scientists report.

"The source of the virus is still not known," but it was not imported from nearby countries, said Dr. Stephan Gunther of the Bernhard Nocht Institute for Tropical Medicine in Hamburg, Germany.

Scientists said they had made the long-sought discovery of how sperm latches onto an egg in the very first spark of reproduction, the outcome of a near decade-long hunt.

The find opens up avenues for new contraception or treating infertility, they said.