Sunday, July 24, 2011
In one experiment, human subjects were given trivia statements and asked to type them on a computer. Half of the students were told in advance that the information would be saved so they could view it later; the other half were told that it would be erased. Those who were told it would be erased had the best recall of the statements later, indicating that their brains were more likely to have made an “emergency backup”, knowing that the information would not be easily accessible again. Those promised computer access to the information later were more likely to forget the information.
In another experiment, half of the students given trivia information were told it would be stored in one of five folders; the other half were told it would be erased. When asked later, the students who were told the information would be in a folder could easily recall which folder it was in; more easily than they could recall the trivia information itself. And as before, they had poorer recall of the trivia information than the students who were told it would be erased.
With easy access to the internet, it seems that we tend to place more importance on where to find information than on memorization. And that’s not necessarily a bad thing…
Friday, July 15, 2011
Nearly three years ago on this blog (see “A Daily Pill Against HIV Infection”, Aug. 10, 2008) I reported that research was underway to determine whether HIV infection could prevented in healthy people by giving them AIDS drugs before they became infected, not after. It’s called pre-exposure prophylaxis (PrEP), and according to a news release from the CDC, there is now convincing evidence that it works!
In one study by researchers from the University of Washington in conjunction with the CDC, a daily pill comprised of two known AIDS drugs (or a placebo) was given to nearly 5,000 “discordant couples” in Kenya and Uganda (one partner HIV-infected, the other not). Uninfected partners who took the daily pill had a 73% lower chance of becoming infected, compared to those who received the placebo. The study was stopped early because the results were so clear-cut that it was deemed unethical to continue withholding the drug from the control group. A second study by the CDC of 1,200 sexually active young adults in Botswana revealed that those who took a daily PrEP pill had a 63% lower chance of infection, compared to those who did not.
Given these recent findings, PrEP is likely to become a new standard of prophylaxis for healthy, at-risk individuals who request it. However, it should be noted that the PrEP pill has not yet been tested in pregnant women, so it may not be for everyone.
Thursday, July 14, 2011
One of the more common sexually transmitted diseases – gonorrhea – is now resistant to three of the four classes of antibiotics traditionally used against it, and is showing signs of increased resistance to the fourth. Gonorrhea became resistant to penicillin and tetracycline in the 1970s and 1980s. In just the past 10 years gonorrhea has become so resistant to the fluoroquinolones that the CDC no longer recommends this class of drugs for treatment of gonorrhea. And now a CDC report reveals that gonorrhea is showing signs of increased resistance to the last class of drugs still generally effective against it, the cephalosporins.
So far, cephalosporin drugs have failed to effectively treat gonorrhea in only three persons – two men in Norway and a woman in Japan. But in U.S. laboratories, the percentage of samples of gonorrhea that show signs of increased resistance to cephalosporins has gone up substantially since 2000. In the Western U.S., for example, 3.3% of the samples showed signs of increased resistance in 2010, compared to 0% in 2000. The numbers vary by state and by region, but the trend is definitely toward increased resistance.
More than 350,000 new cases of gonorrhea are diagnosed in the U.S. each year. A cyclosporine-resistant strain of gonorrhea would be a real problem.
Monday, July 4, 2011
Someday, breathalyzers will be used for a lot more than just determining whether a motorist is drunk. A biotechnology company is working on a desktop device called BreathlinkTM for the rapid identification of pulmonary tuberculosis and other diseases. Researchers are also working on methods for detecting lung and breast cancer; exposure to radiation; air pollution; and the type of volatile organic chemicals typically found in carpets and upholstery. There’s even a breath analysis test for determining whether a heart transplant patient is rejecting his/her new heart. The basic idea is simple; any chemical substance that appears in exhaled air as the direct result of a disease or environmental exposure could be used to diagnose diseases or environmental exposures, provided that the chemical can be detected accurately.
Just how many diseases or environmental substances might be detected by breath analysis, no one knows just yet - as a technique, breath analysis is still in its infancy. But in the not too distant future, breath analysis might become another simple, non-invasive screening method for early detection of disease. Just breathe into this tube, please…..
Friday, July 1, 2011
In India, where there is a strong preference for boys, the girl-to-boy sex ratio among second-order births (the second child) has been declining for several decades. In 2005, for example, there were only 836 second-child girls born for every 1,000 second-child boys when the couple’s first child was a girl – too big a gender difference to be due to natural causes.
Researchers hypothesize that the increased availability of ultrasound is leading to selective abortions of second girls, resulting in anywhere from 4.2 to 12.1 million “missing girls” since 1980. These estimates are backed up by the 2011 Indian census, which reveals that there are more than 7 million fewer girl children than boy children under the age of 6. So here’s a case where an advance in medical science (the development of ultrasound and thus the ability to determine gender long before birth) has resulted in unintended social consequences.
We don’t always know how advances in scientific knowledge will be used by society.