Thursday, February 28, 2008

Probiotic Dietary Supplement Not Always Beneficial

Probiotics are dietary supplements containing beneficial yeasts or bacteria. Available over-the-counter, probiotics are sometimes recommended by nutritionists and doctors as a way to re-establish the body's natural digestive flora after a course of antibiotics. They're supposed to be good for you.

However, a research group testing the hypothesis that probiotics are beneficial in preventing the infectious complications of a specific life-threatening disease (acute pancreatitis) actually found just the opposite. In a carefully designed double-blind, placebo-controlled study of 298 patients at high risk for acute pancreatitis, the patients given a probiotic preparation had a higher death rate (16%) than the controls (6%).

The finding, although startling, should not be used to conclude that probiotics are a bad idea under other circumstances. Obviously we need to know a lot more about probiotics and how they might affect the outcome of specific diseases before we can draw more general conclusions. But for now at least, probiotics should not be given to in patients at high risk for acute pancreatitis.

The original article can be found in the online version of The Lancet (DOI:10.1016/S0140-6736(08)60207-X).

Monday, February 25, 2008

Fear of Genetic Testing

Genetic testing to predict the future risk of specific genetic diseases could significantly improve the delivery of health care (see the Current Issue on pp. 458-459 of Human Biology 5th ed., entitled “The Promises and Perils of Genetic Testing”).

And yet, it appears that many people are avoiding DNA tests out of fear that the information could be misused. They worry that if their DNA test reveals a strong likelihood that they might develop a costly or life-threatening genetic disease later in life, they will become uninsurable even though they are currently healthy (see “Fear of Insurance Trouble Leads Many to Shun or Hide DNA Tests”. The New York Times, Feb. 24, 2008). Insurance companies deny it, of course. But even if insurance companies aren’t currently engaged in genetic discrimination, the commonly held perception that they could is enough to cause some people to avoid DNA tests.

Would your students take a DNA test to determine their risk of developing breast cancer or prostate cancer if those diseases ran in their family? You might ask them.

Wednesday, February 20, 2008

Making Gasoline from Atmospheric CO2

Scientists at Los Alamos National Laboratory have developed a process that could be used to make gasoline from air. Called Green Freedom, the process would use atmospheric CO2 as the source of the carbon in gasoline. This would make gasoline completely carbon-neutral; using gasoline as a fuel would produce CO2 as a waste product, and that CO2 would be converted back into gasoline again.

A non-polluting source of energy would be required to drive the manufacturing process. The most likely candidates would be nuclear or solar power. The process is already technologically possible. The only hitch is that at with current technologies, it would not be economically feasible until gasoline hits $4.60/gallon. But with certain technological advances the break-even price could drop as low as $3.40 per gallon.

See "Green Freedom: A Concept for Producing Carbon-Neutral Synthetic Fuels and Chemicals" at The article could spark an interesting debate among your students about whether we ought to build nuclear power plants to alleviate the greenhouse gas problem.

Your students are too young to remember, but you might remind them that Los Alamos National Laboratory was once a very hush-hush place where the U.S. developed the first nuclear weapons. It is encouraging to see the laboratory converted to peaceful purposes.

Tuesday, February 19, 2008

My Mother's Cells Within Me

Nearly all of us harbor cells that come from a close relative. The phenomenon, called microchimerism, occurs because the placenta is not a perfect barrier to formed cells - sometimes maternal cells make their way into the fetus, and vice versa. Apparently some of these cells live indefinitely in their new host, which is surprising since foreign cells are usually attacked and killed.

Scientists are still working out what the foreign cells may be doing in their host. In some cases they may differentiate into fully functional tissue cells in the host. For example, genetically female heart cells (presumably from the mother) have been found in males. In other cases these foreign cells may trigger immune disorders later in life, when the immune system of the host finally recognizes and attacks the foreign cells. Diseases that may have a microchimerism link include several autoimmune inflammatory diseases of connective tissue (scleroderma, lupus erythematosus, and rheumatoid arthritis), and perhaps even Type 1 diabetes, a disease characterized by poor regulation of blood sugar.

Reference: Nelson, J.Lee. Your Cells are My Cells. Scientific American Feb. 2008, pp. 72-79.

Sunday, February 10, 2008

The Dangers of Antibacterial Soaps

If you're discussing antibiotic resistance of bacteria (p. 18 of Human Biology 5th ed.) or the benefits/risks of breast milk (p. 206) and are looking for an easy-to-read article for your students, take a look at "Fact or Fiction: Do Antibacterial Soaps Do More Harm than Good?" in the February issue of Scientific American (p. 96).

The brief one-page article concludes that for normal healthy people, antibacterial soaps have no apparent health advantage over frequent hand-washing with ordinary soap and water. On the risk side of the risk/benefit continuum, antibacterial additives such as triclosan are showing up in rivers and streams, in agricultural soil, and even in human breast milk. The article certainly would give students something to think about and discuss.