PUBLIC HEALTH: Deaths Among Heroin Users Present a Puzzle

More than 30 heroin users in Scotland and Ireland have succumbed to a mysterious malady in the past 6 weeks, leading health officials to suspect anthrax, the notorious biological warfare agent. Now, analyses by microbe hunters on both sides of the Atlantic offer a somewhat reassuring conclusion: Anthrax did not kill the heroin users. It's unclear what did, but a new suspect has emerged.     

Arthritis. A gene for smooth-running joints

A new study on page 265 of this issue suggests that a genetic defect in mice causes the joint's cartilage cells to pump insufficient amounts of pyrophosphate--a natural water softener--into the joint cleft, and this in turn leads to the formation of bony spurs that eventually stiffen the joints completely. Because humans have an almost identical gene, and disorders such as osteoarthritis also feature an abnormal outgrowth of bones, some arthritis researchers are hopeful that these new findings may point the way toward a new class of pyrophosphate-based drugs similar to the antiscaling chemicals in washing powders and toothpaste. But, as many of the researchers point out, the numerous roads that lead to human joint degradation make a single cure-all unlikely.     

A new way to keep immune cells in check

To avoid being attacked by the immune system, normal cells carry proteins on their surfaces that mark them as "self." Until now, researchers have identified only one type of self marker: so-called class I major histocompatibility complex proteins. Now, on page 2051, a team reports that macrophages, the immune system's scavenger cells, recognize a different inhibitory signal--a protein called CD47. The findings also shed light on the role of CD47, a surface protein present on basically every cell type--and long a molecule in search of a function.