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

Controversial Stem Cell Studies Retracted by Journal

Fraud allegations and waves of criticism from experts have led the journal Natureto withdraw two papers that claimed to describe a breakthrough in stem cell creation.

American and Japanese researchers said they had created stem cells capable of becoming any organ or tissue in the body simply by dipping white blood cells from young mice in an acid bath, the Boston Globereported.

However, an investigation discovered errors and evidence of scientific misconduct in the papers describing the creation of what the researchers called STAP stem cells.

"Ongoing studies are investigating this phenomenon afresh, but given the extensive nature of the errors currently found, we consider it appropriate to retract both papers," Naturesaid in a retraction notice published Wednesday, the Globereported.

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Rare Diseases Targeted in New Research Program

A network of research centers is being established to learn more about rare diseases that individually may affect only a handful of people worldwide, the U.S. National Institutes of Health announced Tuesday.

Doctors at the centers will examine and conduct genetic tests on patients, and share their findings with other experts. By collecting and analyzing this data, it's hoped that doctors will be able to solve these medical mysteries, NBC Newsreported.

Learning more about these rare diseases -- many of which are caused by genetic mutations -- may also provide new insight into more common diseases.

"The Undiagnosed Diseases Network that we are announcing today will focus on the rarest of disorders -- often those that affect fewer than 50 people in the entire world," said Dr. Eric Green, director of the National Human Genome Research Institute, one of the NIH institutes, NBC Newsreported.

"They are so rare that they may never have been discovered or doctors may never have encountered them," he added.