Here are some of the latest health and medical news developments, compiled by the editors of HealthDay:

Virus Creates New Pacemaker in Guinea Pigs' Hearts: Study

A genetically-modified virus turned a part of guinea pigs' hearts into a new, working pacemaker, a new study says.

The virus was injected into the hearts of seven guinea pigs and five later had heartbeats which originated from their new pacemaker, BBC Newsreported.

The U.S. scientists published their results in the journal Nature Biotechnology.

It's likely the same method can be used in humans, but much more animal testing is needed before that could ever be considered, researcher Dr. Hee Cheol Cho, of Cedars-Sinai, told BBC News.

This research "opens up the tantalizing possibility of using cell therapy to restore normal heart rhythm in people who would otherwise need electronic pacemakers," Prof. Jeremy Pearson, associate medical director of the British Heart Foundation, told BBC News.

"However, much more research now needs to be done to understand if these findings can help people with heart disease in the future," he added.


Mandela has Gallstone Operation

Nelson Mandela underwent a successful operation for gallstones on Saturday and remains in hospital for the 10th straight day, officials in South Africa said.

The 94-year-old anti-apartheid hero has undergone tests and treatment for a recurrent lung infection since he was hospitalized on Dec. 8, the Associated Pressreported.

Mandela was leader of the African National Congress and in 1994 became South Africa's first democratically elected president. Mandela was honored in a song at an ANC convention Sunday.

Mandela was hospitalized earlier this year when he underwent exploratory abdominal surgery. Last year, he was treated for an acute respiratory infection, Bloomberg Newsreported.