Quantum cryptography has an uncrackable reputation. A sender typically transmits a message encoded by polarized photons; anyone listening in would cause errors to appear in the reception, alerting the sender and receiver. Researchers at the Massachusetts Institute of Technology, however, show in the April 25 Physical Review A that quantum cryptography can be hacked, at least to a limited extent. They found a way to entangle the polarization of transmitted photons with the momentum of an eavesdropper's photon. By measuring the momentum, the eavesdropper could deduce the transmitted polarizations. Quantum users can breathe easy, though: the trick works for only 40 percent of the data and would not be practical, because the setup requires that the eavesdropper use the same photon detector as the receiver.
Poking Out Lycopene
Lycopene, abundant especially in tomatoes, does not appear to prevent prostate cancer as once hoped (and hyped). Past studies had suggested that a diet rich in the antioxidant could protect against the disease, pre-sumably because lycopene neutralizes free radicals, which are reactive molecules that can damage cells and DNA. In the latest study, a team led by researchers from the Fred Hutchinson Cancer Research Center in Seattle and the National Cancer Institute followed 28,000 men between the ages of 55 and 74. Lycopene and other antioxidants exerted no preventive effect, the scientists found. In fact, in a surprise, the team saw a positive correlation between one antioxidant, beta-carotene, and an aggressive form of prostate cancer. Look up the results in the May 2007 Cancer Epi-demiology, Biomarkers & Prevention.
Pierced to Death
State-of-the-art CT scans appear to have identified the exact cause of death of Ötzi the Iceman, the famous 5,300-year-old glacier mummy found in the Tyrolean Alps. For years, researchers have wondered whether the arrowhead found in his back led to his demise, because people can survive with foreign objects in their bodies. An Italian-Swiss team reports that additional x-rays at the arrowhead site have revealed damage to an arterial wall, a pseudoaneurysm (an arterial bulge typically caused by trauma) and a hematoma-all signs that Ötzi lost massive amounts of blood. Writing online March 15 in the Journal of Archaeological Science, the researchers conclude "with almost complete certainty" that the Iceman bled to death shortly after being shot.
Transplants for Diabetes
Diabetics have dreamed of an injection-free cure, and for decades one great hope has been islet cell transplantation. But since 1974, only about 750 individuals with type 1 diabetes mellitus have received transplants of islets (derived from cadavers), which contain the insulin-producing beta cells, and very few of them achieved insulin independence beyond four years. The shortage of human islet cells and the immune response that rejects them have stifled the goal of making insulin injections obsolete.
So researchers have begun to sidestep these issues by figuring out ways to transplant islet cells derived from pigs, which are in ample supply and produce insulin similar to that of humans. To hide the cells from immune attack, scientists are encapsulating them in a biocompatible semipermeable membrane. But the problem with encapsulation is that it prevents nutrients in the blood from getting to the islets, says Peter Stock, a transplant surgeon who heads the human islet cell program at the University of California, San Francisco. Hence, investigators still need to find a membrane that can obtain nourishment and repel immune cells.
Another way to increase the source of beta cells is with adult or embryonic stem cells, Stock points out. If derived from the patient’s own body, such cells would not set off a transplant-rejecting immune attack. But stem cells may not get around the autoimmune response, the mechanism by which the body of a diabetes patient destroys insulin-making cells in the first place.
A cure for diabetes thus still seems years away. Novel procedures, such as those that encourage spleen cells to convert into beta cells, are promising. And continuing advances in stem cell work— such as the transformation of adult skin cells into stem cells reported in the June 7 Nature—offer much hope.