Rabu, 30 April 2008

Beating the Testosterone Doping Test

According to a study by Swedish researchers, a common genetic deficiency might make it possible for some people to beat the standard testosterone doping test, even if they had been doping with the hormone. The researchers injected 55 male volunteers with testosterone and then tested them with the standard urine test for testosterone doping. More than 40% of all subjects with the genetic deficiency tested negative for testosterone doping over a 15-day testing period.

Two-thirds of the Asian population and about 10% of all Caucasians are deficient in the gene in question. The World Anti-Doping Agency is concerned, but it appears that there is little that they can do about it at this time. Genetic tests would reveal which athletes could beat the testosterone doping test, but genetic testing is not part of the standard anti-doping test for Olympic athletes. Individuals with the genetic deficiency may be able to use testosterone and get away with it, at least until the rules change.

Minggu, 27 April 2008

Atmospheric CO2 Continues to Rise

The National Oceanic and Atmospheric Administration reported this week that the atmospheric levels of heat-trapping CO2 continue to rise, reaching nearly 385 parts per million in 2007. They blame the continued burning of fossil fuels such as coal, oil and gas. Levels of methane also rose, after a decade of relative stability.

If you wish to update the graph on p. 556 of Johnson's Human Biology, 5th ed., place a green dot at 385 ppmv for 2007 and then re-draw the green line from 2000 to 2007. The line is still curving upward, and getting steeper.

Rabu, 23 April 2008

Disposable Hearing Aids

Not many people like the idea of wearing a clunky external hearing aid, and surgically implanted hearing aids are expensive. But soon there may be a better way – disposable hearing aids that slip into the ear canal, out of sight. The new hearing aid, called the Lyric, can be seen at www.lyrichearing.com. The Lyric hearing aid requires replacement every couple of months and costs about $3,000 a year. A magnet is used to turn it on and off or to control the volume.

The Lyric or other products like it may well revolutionize how we correct deficits in hearing, similar to what disposable contact lenses did for eyeglass wearers.

Senin, 07 April 2008

Antibiotic-Resistant Soil Bacteria

A team of Harvard researchers reported in Science this week that hundreds of soil bacteria can tolerate antibiotic concentrations more than 50 times higher than the minimum definition of antibiotic-resistant. A few of them can even thrive on antibiotics as their sole source of carbon. The 11 antibiotics tested by the researchers include such well-known names as penicillin, chloramphenicol, and vancomycin.

None of the antibiotic-eating soil bacteria is a known human pathogen - at least not yet. But bacteria often swap genetic material by a process called conjugation; what if these bacteria were to pass their antibiotic-resistant genes to a truly nasty human pathogen? No one knows how likely this might be at this point.

Instructors will be interested in the original research article (“Bacteria Subsisting on Antibiotics”. Science 320:100-103, Apr. 4, 2008). Students could be given the editorial comment, page 33 of the same issue. Its worth discussing in conjunction with the Health Watch feature on antibiotic resistance in Chapter 1 of Human Biology, 5th ed.

Kamis, 03 April 2008

How Do RNA Interference Drugs Work?

A new drug discovery field called RNA interference is hot, hot, hot these days. According to current theory, small snippets of RNA with just the right sequence should be able to interfere with the expression (translation) of genes with the corresponding complementary nucleotide sequence. Drug companies are racing to find the RNA sequences that would inactivate specific disease-causing genes. Presumably the therapeutic effect would be highly specific, since only certain genes would be inactivated.

But is that how the RNA interference drugs currently under development actually work? New evidence just published online in Nature on March 26 (doi:10.1038/nature06783) suggests that the drugs may be working by a much more general mechanism – activation of the immune system. If so, the drugs may have side effects that have not yet been considered. The findings were such a surprise that the stock prices of small companies working on RNA interference drugs went down briefly.

The Nature article is for experts only. For students, I suggest the more general New York Times article published online on Apr. 2 (“Study is Setback for Some RNA-Based Drugs”, http://nytimes.com/2008/04/02/business/02place.html).
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