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Marijuana may help you unwind — but using it too often could have the opposite effect on your stress response. Researchers say adults who use pot frequently wake up with higher levels of cortisol, also known as the "stress hormone." (7/24)

Results should spark practice change in centers that still use standard fractionation. (Bassett, 7/27)

St. Jude Children's Research Hospital scientists have uncovered a regulatory mechanism for signaling of Sonic Hedgehog (SHH), a pathway essential for embryonic development. The findings, published in Nature Communications, provide insight into how this pathway may be modulated in diseases such as cancer. (7/28)

Microglia are the most common immune cells in the brain, where they defend against intruders and engulf damaged neurons. Now, scientists at Columbia's Zuckerman Institute have discovered for the first time that, just like human neurons, human microglia mature especially slowly compared with microglia in other animals. "This slow development may help human microglia influence the human brain in ways that enable our powerful cognitive abilities," said Carlos Diaz-Salazar, Ph.D., the lead author of a new Neuron study on the subject, who took part in this research while at the lab of Franck Polleux, Ph.D. (7/27)

In a recent study, scientists devised a way of reversing the buildup of compounds that lead to some age-related diseases. (Callaway, 7/24)