Rods (blue) and cones in the human retina
Medical Bliss Physicians less likely than other health professionals to divorce
BUFFER ZONE
Controlling bicarbonate levels may slow progression of eye diseases
BICARBONATE, an important
Within those specialized cells, known as rod and cone photoreceptors, a soluble molecule called cGMP links photon absorption to the electrical activity of a photoreceptor. When it is exposed to light, cGMP is destroyed and ion channels are closed. Positively charged sodium ions cease to enter the rod or cone, and the membrane potential becomes more negative or hyperpolarized. Bicarbonate helps photoreceptors recover from the loss of cGMP by stimulating guanylate cyclase, an enzyme key to the synthesis of cGMP. “By opposing the effect of light, bicarbonate limits the size of the photon response and quickens its recovery,” says lead author Clint Makino, an HMS associate professor of oph-
thalmology at Mass Eye and Ear and director of the Makino Laboratory. “As a result, sensitivity to light is slightly lower, but our ability to track moving objects is improved. An intriguing implication is that vision may change with metabolic state, although further research is necessary to confirm this.” “It is now known,” he adds, “that in some types of retinal diseases, a genetic defect causes cGMP in the rods and cones to rise to lethal levels. Once lost, rods and cones are not replaced, leading to irreversible blindness.” Scientists in the Makino Laboratory want to investigate the possibility that controlling bicarbonate levels in the eye will slow the progress of, or even prevent, eye diseases. —Mary Leach
RALPH C. EAGLE, JR./SCIENCE SOURCE (FAR LEFT); MATTIAS PALUDI
naturally occurring compound in the body, plays essential roles in buffering pH, aiding in digestion, and neutralizing lactic acid produced during physical exertion. Much of the bicarbonate in our bodies comes from carbon dioxide that is produced as waste in all cells as well as from that ingested with certain foods and beverages. Now, a study led by HMS researchers in the Makino Laboratory at Massachusetts Eye and Ear reports that bicarbonate also alters how we see: It modifies the visual signal generated by specialized retinal cells that detect light. The study appeared online March 12 in the Journal of Biological Chemistry.
the largest investigation of divorce rates among physicians has resulted in a finding that may surprise many: Physicians are less likely to divorce than are people in other occupations, including lawyers and other health care professionals. The study, published online February 18 in BMJ, did find, however, that female physicians who worked longer hours had a greater likelihood of divorce than did male physicians. “It’s been speculated that doctors are more likely to be divorced, but no large-scale study has ever investigated whether that is true,” says Anupam Jena, an HMS assistant professor of health care policy at Massachusetts General Hospital and senior author of the report. Previous studies finding higher divorce rates among physicians depended on small, nonrepresentative samples, some from a single institutions, the authors note. Those studies were published three or more decades ago. To get a more comparative and contemporary picture of the divorce rate among physicians, the researchers analyzed data from an annual survey of around three million households conducted by the U.S. Census Bureau. Survey results from 2008 through 2013 included responses from approximately 200,000 health professionals, including more than 48,000 physicians. Although 24 percent of physician respondents had a probability of ever being divorced, the probability of being divorced was 25 percent among dentists and 33 percent among nurses. Only pharmacists, at 23 percent, were less likely than physicians to have been divorced. Female physicians were approximately one-anda-half times more likely to be divorced than male physicians of a similar age. Female physicians who reported working more than forty hours per week had a higher probability of being divorced than those working fewer hours. The apparent impact of hours worked on divorce incidence was the opposite for males. —Sue McGreevey
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