An American man whose HIV seemed to disappear after a blood marrow transplant for leukemia may be showing new hints of the disease, sparking debate over whether a cure was really achieved.

Scientists disagree over the latest findings on Timothy Brown, also known as the "Berlin patient," presented at a conference in Spain last week, according to a report in the journal Science's ScienceInsider blog.

Surgeons said Thursday they had transplanted the first-ever vein grown in a lab from a patient's own stem cells into a 10-year-old girl, sparing her the trauma of harvesting veins from her body.

The groundbreaking procedure may offer hope for patients who don't have healthy veins for use in dialysis or heart bypass surgery, said a paper published in the Lancet medical journal.

An influential British bioethics group says that couples who face the risk of having a baby with certain genetic diseases should be allowed to use eggs from two women to produce the embryo.

Such controversial procedures should only be allowed if they are proven safe, the Nuffield Council on Bioethics said Tuesday, but its advice seems likely to reignite debate. Currently, such treatments are only allowed for research in the U.K., and British law forbids altering a human egg or embryo before transferring it into a woman.

Brazilian researchers say they have successfully tested a vaccine against schistosomiasis, a disease caused by parasitic worms that afflicts more than 200 million people worldwide.

"This is an unprecedented breakthrough in medicine that involved 30 years of scientific work," Dr Tania Araujo-Jorge, of the Oswaldo Cruz Institute in Rio de Janeiro, said Tuesday. The institute receives public and private funding.

Some stem cells can lay dormant for more than two weeks in a dead person and then be revived to divide into new, functioning cells, scientists in France said Tuesday.

The research, published in the journal Nature Communications, unlocks further knowledge about the versatility of these cells, touted as a future source to replenish damaged tissue.

Men who are doctors earn about $12,000 more per year than women doctors, according to a U.S. study published on Tuesday in the Journal of the American Medical Association.

The differences persisted even after adjusting for factors like specialty, academic rank and work hours, said researchers at the University of Michigan Medical School.

Killing vampire bats in a bid to curtail the spread of rabies to humans and livestock may make the problem worse, scientists said Wednesday.

The practice of "vampiricide" in which a poisonous paste is applied to captured animals who spread it to others in mutual grooming back in the roost, does not reduce rabies prevalence, they contend.

U.S. health officials are asking safety questions about the first artificial heart valve designed to be implanted without major surgery, ahead of a meeting this week to consider broadening its use.

Last November Edwards Lifesciences Corp. won approval for its first-of-a-kind Sapien heart valve, which can be threaded into place through one of the body's major arteries. The valve is currently available for patients who aren't healthy enough to undergo the more invasive open-heart surgery which has been used to replace the valve for decades.

Finally, some good news for older fathers. A new study hints that their children and even their grandchildren may get a health benefit because of their older age.

It's based on research into something called telomeres — tips on the ends of chromosomes.

A scientific discovery about where and how cervical cancer takes root in the body has resolved a decades-long mystery and could lead to even better prevention in the future, experts say.

Doctors have identified a peculiar population of stem-like cells in a part of the cervix that when infected by human papillomavirus are responsible for most cases of cervical cancer, according to a study out Monday.