LET THERE BE LIGHT, FOR CATARACT PATIENTS
A new technology may help cataract patients see the light, without glasses. The light-adjustable intraocular lenses may eliminate the need to wear prescription glasses following cataract surgery, of which 3 million are performed each year in the United States. Based on technology developed by researchers from the University of California, San Francisco, and the California Institute of Technology, Calhoun Vision, Inc. is developing a photosensitive silicone intraocular lens, which can be adjusted, weeks after surgery, with a low-power source of light to eliminate refractive errors that may follow implantation. The researchers reported their preliminary findings on the technology at the American Society of Cataract and Refractive Surgery in Philadelphia. Currently, patients experience refractive errors after cataract surgery because of unpredictable wound healing, inaccuracies in pre-operative measurements of ocular dimensions or pre-existing corneal disorders such as astigmatism. "With this technology, we can make power adjustments after the lens is in place, wound healing has occurred, and the eye is stabilized," said Dr. Daniel Schwartz, UCSF associate professor of ophthalmology, director of the UCSF retina division and a co-inventor of the Light Adjustable Lens.
NEW DOOR OPENED TO OLD 'LOCK-AND-KEY' DRUG THEORY
A novel approach may lead to new drug designs for such brain disorders as Parkinson's disease and schizophrenia. The strategy, born of collaborative efforts led by Dr. Richard Mailman of the University of North Carolina, Chapel Hill, School of Medicine, centers around a molecular mechanism called functional selectivity. It builds on research that sheds new light on the classic view of drug action called the "lock-and-key" theory. Under this decades-old idea, the best drugs will be "keys" that only fit a single biological target, or "lock." "Our data now show that we must think not only of the 'lock' and the 'key,' but also about different 'doors' in which the locks are installed. The 'doors' are different organs, or even different parts of the same organs," Mailman said. "Scientists have assumed that one drug would fit and turn all of these identical locks in the same way. Our team's work shows that even though all of the locks may be the same, some keys may only open the locks on certain doors." Based on studies in isolated cells, scientists have suspected the conventional idea may be too simple. The two new papers by Mailman's team take the question to a multi-cell level. The team designed several drugs, including dihydrexidine and propyldihydrexidine, that mimic dopamine by binding to a special type of protein called a dopamine receptor. Under accepted theory, such a drug would function either as an agonist -- causing the same effects as dopamine -- or an antagonist -- blocking dopamine's effects -- at any dopamine receptor, and it would always act the same way, Mailman said. But the new drugs acted as both an agonist and an antagonist in rat studies, he said. "What makes this research noteworthy is that for the first time we were able to show that these mechanisms work not only in cells in the laboratory, but also in the mammalian brain," he said. "Such ideas have important implications for how scientists discover the next generation of drugs because they permit the design or selection of drugs with much more refined mechanisms of action."
BONE-SPARING DRUG
The Food and Drug Administration has approved Actonel for once-a-week prevention and treatment of postmenopausal osteoporosis. The approval offers patients the convenience of a once-a-week dosing option to manage their osteoporosis and protect their bones, researchers said. It will be available in mid-June 2002, by prescription only. "Actonel 35 mg once-a-week is a valuable new tool for the treatment and prevention of postmenopausal osteoporosis," said Dr. Robert Lindsay, chief of internal medicine at Helen Hayes Hospital, professor of clinical medicine at Columbia University and principal investigator of the study. "Patients and doctors always welcome effective new treatment choices, and we now have data that show once-a-week dosing of Actonel is therapeutically equivalent to daily 5 mg dosing."
LEUKEMIA: 12 YEARS IN COMING
Scientists have discovered that a type of childhood leukemia starts with a genetic mutation in the womb and can take 12 years or more to progress into a life-threatening cancer. This is the longest "latency period" yet identified between the initiating genetic event and diagnosis of leukemia. Discovery of such a long time lag between the initial event and full development of leukemia suggests that even some adult leukemia may start in the womb, the researchers said in a report in the journal Blood. The study was led by scientists at the University of California, San Francisco. By studying the similarities in the pregnancies which harbored the initial genetic mutation in this type of leukemia, scientists hope to identify the dietary, environmental or other causes for the potentially harmful mutation. "Unraveling the causes and timing of the mutations that lead to leukemia, may allow us to predict and prevent this devastating disease," said Joseph Wiemels, UCSF assistant professor of epidemiology and biostatistics, who led the research. Three years ago Wiemels and colleagues discovered that another, more common form of childhood leukemia also starts with a mutation in utero. But that leukemia is derived from a different form of blood cell and is confined mainly to ages two to five.
(EDITORS: For more information about CATARACT, call 415-476-2557; about DRUG, call 919-966-2484; about BONE, call 212-477-0472 ; about LEUKEMIA, call 44-20-7424-4749.)
