Rob Stein

Scientists say they have, for the first time, cloned human embryos capable of producing embryonic stem cells.

The accomplishment is a long-sought step toward harnessing the potential power of embryonic stem cells to treat many human diseases. But the work also raises a host of ethical concerns.

Scientists have discovered what may be an important new risk factor for heart disease. And here's the surprising twist: The troublesome substance seems to be a waste product left behind by bacteria in our guts as they help us digest lecithin — a substance plentiful in red meat, eggs, liver and certain other foods.

Doctors say the research further illustrates the complicated relationship we have with the microbes living inside us, and could lead to new ways to prevent heart attacks and strokes.

Scientists say they have found a way to get a glimpse of people's dreams.

"Our results show that we can predict what a person's seeing during dreams," says Yukiyasu Kamitani, a researcher at the ATR Computational Neuroscience Laboratories in Kyoto, Japan.

Philosophers, poets and psychologists have long shared a fascination with dreams. But Jack Gallant, a neuroscientist at the University of California, Berkeley says solving the mystery of our dreams is one tough problem.

This year's flu season started about a month early, prompting federal health officials to warn it could be one of the worst in years. They're urging everyone to get their flu shots.

But like every flu season, there are lots of reports of people complaining that they got their shot but still got the flu. What's up with that?

Well, as Michael Jhung of the Centers for Disease Control and Prevention explains, there are lots of possible reasons.

Geneticist reported Wednesday that they had crossed a threshold long considered off-limits: They have made changes in human DNA that can be passed down from one generation to the next.

The researchers at Oregon Health & Science University in Portland say they took the step to try to prevent women from giving birth to babies with genetic diseases. But the research is raising a host of ethical, social and moral questions.

Scientists in Japan report they have created eggs from stem cells in a mammal for the first time. And the researchers went on to breed healthy offspring from the eggs they created.

While the experiments involved mice, the work is being met with excitement — and questions — about doing the same thing for humans someday.