Monday, May 28, 2007

Scientific American looks at baseball

In a Q&A by SA:

Does the length of a baseball player's arm affect the distance of his throw? If so, how?

Mike Marshall, the 1974 National League Cy Young Award winner and an associate professor of physical education, most recently at West Texas A&M University, winds up and delivers an answer to this one.

When baseball pitchers with various length pitching arms apply the same amount of force, the ones with shorter arms actually achieve higher release velocities. The muscles of players with shorter pitching arms apply their force with greater leverage—so, in order for pitchers with longer arms to achieve the same release velocity, they have to apply a greater force.

To understand how this happens requires knowledge of how muscles move the bones to which they are attached.

As with any human movement, an athlete creates a desired motion by first using some muscles to stabilize the position of one of the bones involved in the action. Then when muscles contract, he or she moves the bone, which is to be put in motion, closer to the one that is stabilized in relation to the body.

In baseball pitching, to achieve their maximum release velocity, a baseball pitcher "locks"—or, stabilizes—the bone in his upper pitching arm (the humerus) to the bones in his shoulder. Then, after rotating his hips, shoulders and upper pitching arm as far as possible toward home plate, he contracts the muscles that move the bones in his pitching forearm, wrist, hand and fingers straight toward home as powerfully as he can.

How fast these bones move toward home plate then determines the release velocity of the baseball. Because shorter forearm, wrist, hand and finger bones have less inertia to overcome, a baseball pitcher can move them faster through release. As a result, with the same amount of force applied, a baseball pitcher with shorter bones in his lower pitching arm can achieve higher release velocities.

Friday, May 11, 2007

Bats in flight - two vortices

I have always been facinated with bats ever since I saw a large gray bat hanging on a stone wall next to my grandparents' house in Harrodsburg, Ky. This is very interesting from Scientific American:

Bats seem to be adapted for slow speed and high maneuverability in the same way as hummingbirds whereas most flying birds are optimized for high speed. As birds swing their wings upward, the feathers separate like window blinds to let air through, which prevents the lift-reducing currents that the bats experienced. The two creatures also leave different wakes: A bat's stretchy wings churn up two separate vortices—one behind each wing—but a pair of relatively rigid bird wings produces one vortex for the whole bird.

Scientists are advising people who build small flying machines to see if the wind tunnel results can help out, giving detailed information about how a small autonomous flying system works. More here.

Sunday, May 06, 2007

Experiemental Biology 2007 - Final Coverage

This is my last update from Experimental Biology 2007 - a meeting too vast to cover all, but here are some last snippets getting news coverage:

* Dr. Martha Payne reported as part of the American Society for Nutritionthat elderly men and women who consumed higher levels of calcium and vitamin D are significantly more likely to have greater volumes of brain lesions, regions of damage that can increase risk of cognitive impairment, dementia, depression and stroke.

Dr. Payne and her co-investigators from Duke and the University of North Carolina examined magnetic resonance imaging (MRI) scans from 232 men and women (79 men, 153 women) between the ages of 60 and 86 (average age 71). All the subjects had at least some brain lesions of varying sizes, including the extremely miniscule ones often seen in even healthy older persons, but those who reported consuming more calcium and vitamin D were markedly more likely to have higher total volume of brain lesions as measured across numerous MRI scans.

“At this point,” says Dr. Payne, “we do not know if high calcium and vitamin D intake are involved with the causation of brain lesions, but the study provides support to the growing number of researchers who are concerned about the effects of too much calcium, particularly among older adults, given the current emphasis on promoting high intakes of calcium and vitamin D.”

* By giving ordinary adult mice a drug - a synthetic designed to mimic fat - Salk Institute scientist Dr. Ronald M. Evans is now able to chemically switch on PPAR-d, the master regulator that controls the ability of cells to burn fat. Even when the mice are not active, turning on the chemical switch activates the same fat-burning process that occurs during exercise. The resulting shift in energy balance (calories in, calories burned) makes the mice resistant to weight gain on a high fat diet.

The hope is that such metabolic trickery will lead to a new approach to new treatment and prevention of human metabolic syndrome. Sometimes called syndrome X, this consists of obesity and the often dire health consequences of obesity: high blood pressure, high levels of fat in the blood, heart disease, and resistance to insulin and diabetes. Dr. Evan’s presentation was part of the scientific program of the American Society for Biochemistry and Molecular Biology.

* Being obese increases the risk of breast cancer in post-menopausal women, shortens the time between return of the disease and lowers overall survival rates. Researchers now report evidence on how leptin, a hormone found in fat cells, significantly influences breast cancer development and progression in mice. This new understanding, says Dr. Sebastiano Ando, establishes a new mechanism for the link between obesity and breast cancer and suggests new targets for drugs that could intervene in that mechanism.

Dr. Ando’s presentation was part of the scientific program of the American Society of Investigative Pathology.

* Recent findings that the widely-used herbal supplement Saint John’s wort could dramatically affect the absorption and metabolism of many prescription and non-prescription drugs raised concerns that other popular herbal supplements might cause similar changes, thus significantly altering drugs’ therapeutic or toxic effects. What, for example, about ginseng and ginkgo biloba, two of the most widely used herbal supplements in this and other countries?

Speaking at Experimental Biology 2007 in Washington, DC, Dr. Gregory Reed reported a study that found daily use of ginseng or ginkgo biloba supplements at the recommended doses, or the combination of both supplements, are unlikely to alter the pharmacokinetics - by which drugs are absorbed, distributed, metabolized, and eliminated by the body - of the majority of prescription or over-the counter drugs. Dr. Reed’s presentation was part of the scientific program of the American Society for Pharmacology and Experimental Therapeutics.

Tuesday, May 01, 2007

Smelling for the first time

Experimental Biology 2007 update:

New discoveries about the biochemical basis of the majority of cases of the congenital inability to smell any odor, no matter how strong, have enabled their discoverer, Dr. Robert I. Henkin, director of The Taste and Smell Clinic in Washington, DC, to treat such patients, enabling them to smell something for the first time in their lives.

These patients respond with amazement, Dr. Henkin told fellow scientists .

“Until the treatment began to take effect, they had never experienced the olfactory world that surrounds us all, and it is with excitement that they quickly begin to learn what different things smell like and to relate those odors to objects they have known all their lives,” says Dr. Henkin.

His study is the first to characterize the biochemical abnormalities in these patients and the first to successfully treat patients using this new understanding. Dr. Henkin’s presentationwas part of The American Physiological Society.

In the United States alone, there are about 400,000 people who have never smelled anything in their lives. This does not include those who lose their once normal smell function because of illness or accident. A relatively small percentage - 12 percent - of individuals with congenital smell loss have multiple anatomical abnormalities of the brain and other organs. The vast majority - 88 percent - of individuals with congenital smell loss, however, do not have any such obvious organ abnormalities and their olfactory nerves and the brain regions that process olfactory information are intact.

Why, then, have they never been able to smell?

After determining the family of enzymes to which the growth and death factors belong and defining the biochemical pathway responsible for these factors, Dr. Henkin was able to treat these patients with PDE inhibitors that increase the concentration of growth factors and inhibit the secretion o death factors in nasal mucus. The treatment has been successful in restoring smell function in some of these patients, with the higher the dose and longer the use having the greatest effect.