FRIDAY, July 11 (HealthDay News) -- Teach parents how to talk about sex with their teen, and they will tackle this tough subject more readily and often, a new study says.

MONDAY, June 23 (HealthDay News) -- Newly-identified stem cells located on the surface of the heart give rise to heart muscle cells, say researchers at Children's Hospital Boston.

They believe the finding may lead to ways to regenerate injured heart tissue.

In previous research, the Children's team found that two types of stem cells (progenitors) marked by activity of the genes Nkx2-5 and IsI1 form many components of the heart. In this new study, the team identified another progenitor, marked by expression of a gene called Wt1, that gives rise to heart muscle cells.

TUESDAY, June 3 (HealthDay News) -- At least 40 percent of American infants and toddlers aren't getting enough vitamin D, according to researchers from Children's Hospital in Boston.

Twelve percent of the youngest children in the United States are already deficient in vitamin D, and another 28 percent are at risk for vitamin D deficiency, according to the study, which appears in the June issue of the Archives of Pediatrics and Adolescent Medicine.