Brief Updates from the World of Science

• Researchers studying the science of sprinting now believe that the top speed a human runner can attain is close to 40 mph. Currently Usain Bolt holds the world record in the 100-meter dash with a top speed of 28 mph. A common belief was that impact forces on legs of runners limited speed. Research by Wyoming University scientists now suggest that legs easily handle running forces, and that the real limitation on running speed is the rate of muscle contractions that propels the legs. Someday, a runner with just the right leg musculature will break the present record in the 100-meter dash and replace Bolt as the world’s fastest human. (The Week, Feb. 12, 2010)

• In mammals sound is amplified by specialized cells, called hair cells, that line the fluid-filled inner ear chamber. Sound energy subtly disturbs the fluid, which in turns causes the elongated hair cells to move. The amount of movement is detected by nerve endings, and signals are transmitted to the brain for interpretation. Simply put, lots of fluid disturbance means lots of hair cell movement, and the brain alerts us to a BIG noise. Recently, scientists discovered that a protein in the surface of hair cells is the key to amplifying sound. The protein, called prestin, allows certain bats and whales to echolocate. These animals produce sounds in the form of high-pitched chirps, squeaks, and clicks, and it is prestin in their hair cells that is tuned to detect the reflections of these sounds from objects in the environment. In mice where prestin genes were suppressed, 40 – 60% of their sensitivity to sound was lost. (Current Biology, Jan. 26, 2010)

• Although farm-raised salmon account for about three-quarters of the fresh and frozen salmon sold in the U.S., Target stores announced that they will no longer market farmed salmon. This action was taken (in their words) “To ensure that its salmon offerings are sourced in a sustainable way that helps to preserve abundance, species health, and doesn’t harm local habitats.” In the future, Target will buy wild-caught salmon from Alaskan fisheries. To become better informed about farm-raised fish, Google “farm raised salmon.” (J. Birchall in Financial Times, Jan. 26, 2010)

• Do antidepressants really work? Newsweek (Feb. 8, 2010) published a lengthy article addressing this question. It was based on a recent article in the prestigious The Journal of the American Medical Association claiming that antidepressants work no better than placebos for people with mild or moderate depression. Reputable studies reported that patients improved about 75% as much on placebos as on the real pill. It is often difficult to evaluate the effects of antidepressants because drug firms avoid publishing studies that show their pill has no effect over that of a placebo. Further, there is no direct evidence of the mechanism of action of the so-called SSRI drugs (selective serotonin reuptake inhibitors). No doubt they can relieve mild depression over the short-term, and perhaps for some individuals they are effective long-term. “Depression is a highly individualized illness, and not all patients respond the same way to a particular treatment,” said one expert. Another said: “The placebo effect gets you pretty far, but for those with very severe, more chronic conditions, it’s harder to knock down and placebos are less adequate.” Although psychotherapy is more effective than antidepressants, for most people it is cost-prohibitive. The bottom line is if you continue to find relief in your antidepressant, continue to take it – but stay informed.