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Vol. LX, No. 17
August 22, 2008
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Digest

  A new drug therapy used to treat abnormal swelling in the eye—diabetic macular edema—has proven less effective than traditional laser treatments.  
  A new drug therapy used to treat abnormal swelling in the eye—diabetic macular edema—has proven less effective than traditional laser treatments.  

Older Treatment May Be Better for Saving Sight in Some with Diabetes

A new drug therapy used to treat abnormal swelling in the eye—a condition called diabetic macular edema—proved less effective than traditional laser treatments in a study funded by NEI and published online in Ophthalmology. The study demonstrates that laser therapy is not only more effective than corticosteroids in long-term treatment of diabetic macular edema, but also has far fewer side effects. Between 40 and 45 percent of the 18 million Americans diagnosed with diabetes have vision problems such as diabetic macular edema. This condition occurs when the center part of the eye’s retina called the macula swells, possibly leading to blindness. Ophthalmologists traditionally use lasers to reduce the swelling. However, starting about 5 years ago, early reports of success in treating the condition with injections of a corticosteroid— triamcinolone—led to a rise in popularity of this alternative therapy. This is the first study to compare the long-term benefits of both treatments.

Study Suggests Improved Pain Treatments

Two chemicals associated with neurodegeneration and inflammation play important and distinct roles in development of neuropathic pain, according to a study funded in part by NINDS. The findings, reported in Nature Medicine, may lead to new treatments that can stop neuropathic pain from developing and alleviate it after it begins. Scientists studied how enzymes called matrix metalloproteinases (MMPs) affect the development of neuropathic pain. Previous research has shown that MMPs play important roles in the inflammation and tissue remodeling associated with some neurodegenerative diseases. Researchers studied MMP-2 and MMP-9 in rodents with a spinal nerve injury. By selectively blocking MMP-9 and MMP-2, the investigators showed that neuropathic pain responses depended on MMP-9 for the first several days after injury. MMP-2 then prompted changes that helped to maintain the pain. The study is the first to show that neuropathic pain has different phases and that the phases are controlled by different MMPs.

Scientists Develop Sensitive Salivary Sensor

For people who dislike needles, medical tests that require a drop of saliva instead of a vial of blood will one day make a trip to a doctor or dentist much easier. But as scientists now construct the first of these saliva tests for early signs of cancer and other diseases, they continue to push the technological envelope in interesting ways. As published in Biosensors and Bioelectronics, a team of researchers supported by NIDCR report they have developed an ultra-sensitive optical protein sensor, a first for a salivary diagnostic test. The sensor can be integrated into a specially designed lab-on-a-chip, or microchip assay, and preprogrammed to bind a specific protein of interest, generating a sustained fluorescent signal as the molecules attach. A microscope then reads the intensity of the fluorescent light—a measure of the protein’s cumulative concentration in the saliva sample—and scientists gauge whether it corresponds with levels linked to developing disease. In their initial experiments, the scientists primed the optical protein sensor to detect the IL-8 protein, which at higher than normal concentration in saliva is linked to oral cancer. Using saliva samples from 20 people—half healthy, the others diagnosed with oral cancer—the sensor correctly distinguished in all cases between health and disease.

New Study Results Explain How Dormant Tumor Cells Become Active Later

Scientists using a three-dimensional cell culture system have identified a mechanism by which dormant, metastatic tumor cells can begin growing again after long periods of inactivity. Results of the NCI study appeared in the Aug. 1 Cancer Research. The new findings indicate that the switch from dormancy to proliferative, metastatic growth may be regulated, in part, through signaling from the surrounding microenvironment. Targeting this mechanism may also provide strategies for inhibiting the switch from dormancy to proliferation. Recurrence of breast cancer often follows a long latent period in which there are no signs of cancer; metastases may not become clinically apparent until many years after removal of the primary tumor and follow-up therapy. According to one study leader, NCI’s Dr. Jeffrey Green, “Recent evidence suggests that, in many cases, tumor cells have already seeded metastatic sites even when the primary tumor is diagnosed at an early stage.” Approximately 30 percent of breast cancer patients diagnosed with early-stage disease have been found to have breast cancer cells in their bone marrow. However, these cells seem to exist primarily as micrometastases that do not manifest themselves clinically in any way.—

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