Sunday, December 28, 2008

Exercising Your Head Cold

When you catch cold, should you continue your usual exercise routine or just stay at home and rest?

According to a pair of articles published about 10 years ago, maintaining your usual exercise regimen may be good for you when you have a cold, or at least it will do no harm. A typical head cold with a runny nose and sneezing does not affect lung function or exercise capacity. And although exercise doesn’t actually speed recovery time, people who continue to exercise during a head cold tend to report that they feel better than people who don't exercise. So the next time you catch a cold, go ahead and continue doing whatever exercise you enjoy doing.

"Effect of rhinovirus-caused upper respiratory illness on pulmonary function test and exercise responses". Weidner TG et al. Med. Sci. Sports Exerc. 29:604-609, 1997.
"The effect of exercise training on the severity and duration of a viral upper respiratory illness". Weidner TG et al. Med. Sci. Sports Exerc. 30:1578-1583, 1998.

Friday, December 19, 2008

Detecting Protein Markers of Disease

Certain diseases are characterized as having specific abnormal proteins circulating in their blood. These proteins could serve as markers of the presence of the disease. However, the current clinical laboratory tests for these proteins are expensive, making screening millions of people for these diseases impractical. Generally, the only people who are tested are those who are at risk or who are already suspected of having the disease.

A technique just now being developed would make testing for the presence of abnormal plasma proteins easy, quick and cheap. The technique is based on glass and plastic microfluidic chips that can test for dozens of proteins in a single drop of blood, in just minutes, for pennies per test. The new technique is described in the Dec. 19 issue of Science.

Thursday, December 18, 2008

Incentives for Organ Donations

There are now over 100,000 patients waiting for an organ transplant. Over 6,000 of them will die this year because they will not find a suitable organ in time. The problem, as discussed in Human Biology 5th ed. (pp. 368-369), is simply too few available organs for too many patients. Aside from the fact that finding a good match among unrelated donors is relatively rare, healthy people are often reluctant to donate an organ for emotional reasons and there is no financial incentive for organ donations. In fact, current federal law states that a person can go to jail and be fined $50,000 if “valuable consideration” is given to a donor. The law was meant to discourage commercial trafficking in human organs (considered to be exploitive of the poor), but it has also had a chilling effect on altruistic giving.

But that may soon change. Senator Arlen Specter of Pennsylvania will introduce a bill next year that would allow states to offer certain “incentives” to donors and their families, such as tax credits, contributions to 401K retirement plans, and tuition vouchers. The bill still would still prohibit the direct buying and selling of organs, however, so you won’t be able to buy a kidney on eBay any time soon.

One patient’s emotional odyssey as her kidneys began to fail is described in “Desperately Seeking a Kidney” published two days ago in the New York Times. It might make an interesting additional reading assignment for your students.

Wednesday, December 17, 2008

Frozen Embryo Dilemma

Fertility treatments and IVF procedures generally produce more viable embryos than are needed in order to achieve a successful pregnancy. So after a couple has a child by IVF, they must decide what to do with the “leftover” embryos. There are at least five choices: 1) freeze and save them for several years in case they choose to have more children, 2) discard them, 3) donate them for research, 4) donate them to another couple, and 5) leave them frozen until some other decision is made.

A recent survey published in the journal Fertility and Sterility (online Dec. 5) indicates that the decision is a difficult one, even for couples that do not want any more children. Over 40% would not feel comfortable discarding the embryos. And even though they no longer needed them for themselves, over 50% would not consider donating their embryos to another couple. Common reasons given were because they wouldn’t want their child brought up by another couple or because of the fear that their child might meet an unknown sibling someday. Forty percent would consider donating their unused embryos for research, but that option is not available at all IVF clinics. Faced with what they view as unacceptable options, twenty percent say they will keep the embryos frozen indefinitely. However, frozen embryos may not be viable after several decades, so this may ultimately be a decision to let the embryos die.

There are now more than 400,000 frozen embryos at IVF clinics. The authors of the survey suggest that potential parents need to be counseled thoroughly about the choices ahead of them before they choose IVF, not after.

What would your students choose to do if they had leftover embryos?

Tuesday, December 9, 2008

Alzheimer's Disease Linked to a Virus

Alzheimer’s disease is a debilitating disorder of the elderly characterized by severe, progressive loss of memory, confusion, irritability, and withdrawal. The disease develops because amyloid plaques accumulate in the brain, interfering with neural transmission. But why do these plaques develop in some elderly persons but not others?

A recent paper in the Journal of Pathology (217:131-138, Jan. 2009) offers some tantalizing clues. It appears that two factors may be involved; 1) a genetic predisposition to Alzheimer’s disease, and 2) chronic infection of the brain with the same virus that causes cold sores; Herpes simplex type 1. The herpes virus is present in the brains of a high proportion of elderly persons. In the absence of the genetic predisposition to Alzheimer’s the virus doesn’t seem to do much. But in elderly patients with the genetic risk factor for Alzheimer’s, the virus is associated with amyloid plaque accumulation and may in fact be the cause of the plaque formation. If this turns out to be correct, Alzheimer’s disease may some day be preventable with a vaccine.

I am reminded of another chronic disease - peptic ulcers - that turned out to be caused by an infection, in this case by a bacterium called Helicobacter pylori (see Human Biology, 5th ed., p. 328).

Monday, November 24, 2008

Re-creating Extinct Animals

According to a recent article in the New York Times, advances in DNA sequencing and genetic engineering techniques are leading to cautious optimism among scientists that someday it may be possible to bring extinct animals back to life. But it will not be easy. DNA undergoes decay after death, falling apart into little pieces within about 60,000 years. Determining the correct sequence of an extinct species’ DNA requires special DNA sequencers that can analyze the tiny pieces and then calculate how they were aligned in the original intact molecule.

The second step would be to actually reconstruct the deciphered DNA code back into intact DNA once again. One way would be to “reverse engineer” the DNA of a close living relative species until it is similar to the known sequence of the extinct species. So far this has not been possible because of the sheer numbers of base pairs (perhaps half a million) that would need to be modified. But researchers are hopeful that techniques will be available soon to modify up to 50,000 sites at a time. The extinct species’ DNA would then be inserted into an egg of the living relative and incubated in that relative until birth.

How would your students react if it were to be announced one day that an extinct human such as a Neanderthal had been reverse engineered and then born to a modern human or a primate mother?!

Thursday, November 20, 2008

Ginkgo Doesn't Prevent Dementia

According to a study in the Journal of the American Medical Association, daily doses of the popular herbal antioxidant Ginkgo biloba neither prevent nor delay the onset of dementia (cognitive impairment). The most common type of dementia is Alzheimer’s disease.

Herbal extracts of Ginkgo remain popular as a memory enhancer, even though previous scientific evidence showed that Ginkgo just doesn’t enhance memory. So don't expect this latest finding regarding dementia to put much of a dent in Ginkgo’s annual sales of over $200 million. Good marketing apparently trumps good science.

Thursday, November 13, 2008

Surrogate Grandmother

According to an Associated Press article that appeared in many major newspapers and news services yesterday, a 56-year-old woman gave birth last month to triplets. The event was noteworthy because the three baby girls were actually her biological granddaughters.

Apparently a young couple could not conceive because the woman had had a hysterectomy. So they used in vitro fertilization (IVF) to produce their embryos, which were then implanted into the young woman’s 56-year-old mother.

My class took quite an interest in the many and varied reproductive possibilities raised by modern IVF techniques. They understood the obvious benefit, which is to enable some infertile couples to have children of their own. They also quickly grasped that it could also be used (in combination with preimplantation genetic diagnosis) to choose a child’s sex, to avoid having a child with certain genetic disorders, or even to cure an older sibling of a genetic disorder (See the Current Issue in Human Biology 5th ed., pp. 396-397). But they didn’t come up with this scenario!

Tuesday, November 11, 2008

Whatever Happened to Golden Rice?

Golden rice was once heralded as a cure for vitamin A deficiency, which kills or blinds children in poorer countries worldwide. But twelve years after its development golden rice is still not being produced and distributed. The primary reason is categorical opposition to all genetically engineered (GE) foods by organizations such as Greenpeace. Greenpeace argues that although golden rice might indeed benefit vitamin-deficient children, acceptance of golden rice would open the door to other GE crops that Greenpeace vehemently opposes.

In the face of intense, well-organized opposition, government regulatory agencies have been reluctant to approve GE crops, including golden rice. The company holding the patent on golden rice eventually gave up, saying there was no money in it. It's still being studied in a few labs by humanitarian organizations such as World Food Day, but don’t expect to see it on grocery shelves any time soon. That's too bad, for golden rice really is a product that could help people in need, as opposed to just helping food producers and manufacturers.

Sunday, November 2, 2008

New Nutrient Standards for Packaged Foods

Finally, someone has decided to make it easy for consumers to pick the healthiest packaged foods! A coalition of some of the biggest food companies has teamed up with scientists and the federal government to develop and promote a simple front-of-package logo called “Smart Choices” to indicate that a food meets certain nutritional standards. The standards include limited quantities of total and saturated fats, cholesterol, added sugars and salt, as well as minimum quantities of nutrients for good health, such as calcium, potassium, fiber, and certain vitamins. And like the “Heart Healthy” program originally developed by the American Heart Association, the new program is based on good scientific evidence.

Once consumers understand what the logo means and accept its underlying health assumptions, they can simply look for the logo on the front of the package. “Pattern recognizers” such as myself (who can’t find their favorite products in the grocery store if the manufacturer changes the packaging!) will appreciate the help in picking healthful foods. The logo is a green check mark in a square along with the words, “Smart Choices Program”. For a complete listing of the nutritional requirements to earn the Smart Choices label, visit the Smart Choices website. The logo should begin appearing on products in stores by the middle of next year.

Friday, October 24, 2008

Who Were the Flores People?

Since their discovery in 2004, the origin and identity of a diminutive people who lived on the island of Flores, Indonesia 70,000 to 12,000 years ago have been the hot topic among paleoanthropologists (see the Current Issue in Human Biology 5th ed., pp. 520-521.) The discoverers immediately claimed to have unearthed a new human species, which they named Homo floresiensis. Nay-sayers still dispute the claim, saying that the one skeleton found so far, named LB1, is nothing more than a diseased human with microcephaly.

Well, it seems that the new-species proponents are gaining ground these days. Analysis of LB1’s hands and feet suggest that this is not the skeleton of a modern but diseased human. Her wrist bones and especially her feet are closer to those of Homo erectus, an African Hominid that lived in Africa more than a million years ago. Her feet are so long that scientists think she must have walked with a high-stepping gait and been a poor runner. How Homo floresiensis reached Indonesia and survived there for over 50,000 years is a mystery.

For a good look at the one skeleton unearthed so far, see “When Hobbits (Slowly) Walked the Earth”, Science April 25, 2008, pp. 433-435. You can get the article online at - search for "When Hobbits".

Wednesday, October 15, 2008

What's in That Energy Drink?

How much caffeine is there in those so-called “energy drinks”? Take a look at the article in press in the journal Drug and Alcohol Dependence (2008) by C.J. Reissig, et al., entitled “Caffeinated energy drinks – A growing problem”, available online at According to Table 1 in the article, some of them are pretty high-powered. Most energy drinks have about the same caffeine concentration as brewed coffee, but considering that some drinks come in 16- or even 24-oz sizes, that's a lot of caffeine.

Sales of these products continue to climb. Health officials are growing increasingly concerned by reports of acute caffeine intoxication, dependence, and withdrawal among children. There is also a trend toward the combined use of energy drinks and alcohol among young adults.

Which ones do your students drink? Do they know what’s in them?

Tuesday, October 14, 2008

Portable Music Players and Hearing Loss

In Human Biology, 5th edition we warn that portable music players are capable of sound levels that could permanently damage one’s hearing (“Do Portable Music Players Endanger Your Hearing?” p. 293). A commission of the European Union apparently agrees. In an opinion made public yesterday, the EU Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) concluded that users of portable music players who listen at high volumes for more than an hour a day risk permanent hearing loss. Their best guess is that 5-10 percent of listeners, or up to 10 million people in the EU, fall into that category. They warn that although listening at high volumes may not seem to have an immediate effect, it still may lead to hearing loss later in life.

The European Commission is planning a conference for early 2009 to discuss the committee’s findings with industry, consumers, and governments, and to consider whether there is a need for tighter controls over portable music players. I would not be surprised to see new legislation emerge that limits the maximum sound volumes attainable with portable music players.

SCENICOR’s 80-page preliminary report, released in June for public comment, is available online.

Monday, October 13, 2008

Ginkgo and Prevention of Stroke

The herbal remedy Ginkgo biloba may help prevent strokes, according to researchers at Johns Hopkins University. The researchers induced strokes in mice after treating some of the mice with various doses of Ginkgo. The mice pretreated with Ginkgo had nearly 50 percent less brain damage after stroke than the untreated mice. The researchers speculate that Ginkgo may be protective against stroke because it increases the level of an antioxidant enzyme that eliminates free radicals. And free radicals reportedly have damaging effects in living cells, even after a stroke-causing clot is removed or dissolved.

Researchers caution that so far, the research has only been done on mice. Still, it’s encouraging to see herbal remedies being subjected to the same kind of careful scientific scrutiny that has traditionally been applied to therapeutic drugs. This is exactly what we had hoped for, as discussed in Human Biology 5th ed. in the Current Issue essay entitled “Antioxidants: Hope or Hype?” (pp. 42-43). In time perhaps we’ll know the real story behind herbal remedies, and not have to rely on anecdotes and hype.

Thursday, October 9, 2008

New Drug Test for Athletes

The International Olympics Committee plans to retest many of the nearly 1,000 blood samples it collected during the 2008 games in Beijing for a synthetic analogue of the natural hormone erythropoietin, called CERA. CERA is a so-called “designer drug” that was supposed to escape detection. But a test is now available to detect CERA, and several Tour de France cyclists subsequently were found to have used it.

According to World Anti-Doping Agency rules, an athlete’s blood may be retested for up to eight years after an athletic event. The International Olympics Committee keeps blood samples for eight years for situations like this, in which a new test is developed to detect a previously undetectable performance-enhancing drug. It’s just another way that sports authorities try to keep up with athletes who are willing to cheat. Sports authorities hope that the knowledge that an athlete might still be stripped of his/her medals up to eight years after a competition will deter some athletes from using drugs in the first place. But the desire to win is strong, and no one knows if the strategy will work.

Wednesday, October 8, 2008

More on Sequestering Carbon

A good article on current and future methods of carbon sequestration for reducing greenhouse gases is “Down with Carbon” (Science News May 10, 2008, pp. 18-23.) The article is written at a level that students will understand. Some promising possibilities for long-term storage include the bottom of the ocean, in sandstone/saline aquifers deep underground, or in volcanic rock formations. There are also some interesting synthetic materials called zeolites in development that can soak up carbon.

Instructors will be interested in the detailed report by the Intergovernmental Panel on Climate Change (IPCC) entitled “Carbon Dioxide Capture and Storage – Summary for Policymakers”. The article has some great illustrations that would be useful in teaching. They can be used free with acknowledgment.

Saturday, September 27, 2008

Carbon Sequestration

A currently feasible technology for sequestering carbon so that it can't contribute to global warming is to store it deep underground. Take a look at the procedure used at Statoil of Norway’s Sleipner West gas field. Statoil is storing 2,800 tons of CO2 deep underground every day, in what is currently the largest carbon sequestration project in the world. Their website has a nice animation that shows the chemical process for separating the CO2 from natural gas, as well as a good reference article that your students could read and understand. We talk about carbon sequestration in the upcoming 5th edition of Human Biology, in the Current Issue on global warming (pp. 556-557).

Wednesday, September 24, 2008

A Screening Test for Ovarian Cancer?

Here’s an ethical dilemma for you:

A promising new screening test for ovarian cancer called OvaSure can correctly identify ovarian cancer 95% of the time. Ovarian cancer is one of the most deadly cancers if it is not detected early. The company marketing the test says that the test has a false-positive rate of only 0.6%. (A false-positive is when the test indicates that cancer is present when in fact it is not.) Should the test be made widely available as a screening test for ovarian cancer?

Let’s see; 95% success rate at detecting ovarian cancer versus a 0.6% false-positive rate – it doesn’t sound like much of a dilemma, does it? But it is an interesting dilemma, and the reason is that ovarian cancer is rare; its prevalence is only about 0.06%. So among 100,000 women screened with the new test, 60 (0.06% of 100,000) would have ovarian cancer and 57 of them (95%) would be diagnosed correctly. Many of these 57 might be saved. However, 600 women (0.6%) would be told they had ovarian cancer when they did not. In the absence of any good corroborating tests to confirm the diagnosis, many of those 600 women might choose to have a surgery they actually didn’t need. And almost certainly they'd suffer emotionally from the belief that they had a deadly cancer.

Sometimes you have to run the numbers carefully to see the full effect of what is being said. It pays to be a skeptic.

ADDENDUM: Ovasure was pulled from the market in October, 2008, after the FDA sent the company a letter saying that the kits required FDA approval before they could be marketed and sold.

Saturday, September 20, 2008

Gender Selection Nears Perfection

In Human Biology 5th ed., pp. 396-397, we talk about some of the ethical and technical aspects of gender selection of a baby, and we mentioned sperm sorting followed by artificial insemination as a way of increasing a couple’s chances of having a boy to over 75%, a girl to over 90%.

Well, if those odds still aren’t good enough, now gender can be selected with essentially 100% accuracy. Basically, it’s a variation of the standard in vitro fertilization (IVF) technique: 1) harvest eggs from a woman according to the standard IVF protocol, 2) fertilize the eggs in vitro, 3) grow the embryos to the 8-16 cell stage, 4) Remove a cell for DNA analysis to determine the presence or absence of the Y chromosome, 5) implant only embryos of the desired sex. Bingo, it’s a girl! (Or a boy).

Removing a cell for DNA analysis doesn’t affect the ultimate development of the fetus because at that stage none of the cells have begun to differentiate. In fact IVF with DNA analysis is already being done to screen out certain rare but debilitating genetic diseases, where the risk of these diseases is considered high. But before a couple chooses to use it to select gender, they should consider that it’s expensive, it’s invasive, and some would say it goes against nature.

Where do your students stand on this? Are they aware that there are clinics advertising on the Internet that are routinely doing it? (Google “IVF” and “gender selection”).

Friday, September 12, 2008

Irradiation of Foods

Would your students buy lettuce and spinach that had been irradiated in order to kill micro-organisms such as E. coli and salmonella? In fact, the government has already approved of the practice. Irradiation of oysters, beef, poultry and eggs has been allowed for some time now, but irradiation of lettuce and spinach is fairly new.

Until now the market for irradiated foods has remained small because current FDA regulations require that irradiated foods be labelled as “irradiated” and display an irradiation logo. The labels have convinced some consumers that irradiated foods may be radioactive (they’re not). To encourage consumer acceptance, the FDA has proposed changes to the labelling rules so that in the future, irradiated foods would only have to be labelled as “cold pasteurized”, or simply pasteurized.

How accurate are your student’s perceptions about food irradiation? How many of them mistakenly believe that irradiated foods are radioactive? The safety of food irradiation might make a good out-of-class research project or topic for discussion.

Tuesday, September 9, 2008

Strong Hurricanes Get Stronger

This week marks the peak of the hurricane season for 2008. And a new study just published in Nature shows that the strongest hurricanes are getting stronger. The strongest storms now have peak wind speeds that average 16 miles/hour faster than back in 1981 (see “The increasing intensity of the strongest tropical cyclones.” Nature Sept. 4, 2008, pp. 92-95.) The article is not suitable for students, however, unless they have a strong background in statistics.

Over the same time period (1981-2006), the sea surface temperatures have risen by 0.5 degrees Fahrenheit. Most climatologists believe that warmer waters are certain to lead to stronger storms, because hurricanes derive their energy from the heat of warm surface waters.

Friday, September 5, 2008

Bird Flu: The Pandemic That Hasn't Happened (Yet)

When was the last time YOU thought about bird flu? These days the public and the news media are treating the continued threat of a worldwide pandemic with a great big yawn. Bird flu is so yesterday!

Here’s an interesting exercise you could give your students: Ask them to search a key phrase such as “bird flu”, “avian influenza” or “H5N1” in any major newspaper with a searchable archive (such as the New York Times), arrange the retrieved documents by date, and count them. I searched “avian flu” in the New York Times recently and found that references peaked at 181 in 2006 and have since fallen to a paltry 18 in the first eight months of 2008.

Psychologists surely would have something to say about how long we can sustain our fear of a perceived threat that doesn’t materialize quickly. Health officials worry that if we become convinced that bird flu is not a threat any more, we will begin to make political and economic choices that direct our resources away from preparedness programs. And no one knows whether or not that would be a good idea at this point.

What do you think?

Monday, September 1, 2008

Limits to the Human Population

In Human Biology: Concepts and Current Issues, 5th ed. we describe the theoretical limits on any population’s growth (Figure 23.2) and show the growth of the human population since the dawn of human history (Figure 23.3). How close is the current human population of 6.8 billion to Earth’s human carrying capacity? According to Jeffrey Sachs, Director of the Earth Institute at Columbia University, “We still do not really know”.

See “The Specter of Malthus Returns”. Scientific American September 2008, p. 38. Your students could read and appreciate Dr. Sachs’ one-page opinion piece on the subject. In my class the article led to a spirited discussion of the wide disparities in resource utilization by different countries.

Monday, August 25, 2008

Measles is on the Rise

According to the Centers for Disease Control and Prevention (CDC), there were more cases of measles in the U.S. in the first 7 months of 2008 than at any comparable time in the past 12 years. There have also been measles outbreaks in Switzerland, Italy, Israel, and Britain in recent years. The most likely reason is that an increasing number of children have not been vaccinated against the disease because some parents believe that vaccinations cause autism. Health officials contend that there is no connection between vaccinations and autism, but many parents remain unconvinced.

Measles is highly contagious, so it is no surprise that it may be among the first vaccine-preventable diseases to reappear when vaccination rates decline. Fortunately, measles is not very virulent; most patients are treated at home and recover without any long-term consequences. But if the return of measles is an early indication of lower vaccination rates, it may only be a matter of time before other vaccine-preventable diseases return as well. And that has health officials worried.

How do you feel about childhood vaccinations?

Sunday, August 24, 2008

Sensing Danger in the Air

Scientists have long known that some animals can sense danger in the air, but little was known about how they did it. Now they have a clue. According to a report in Science, specialized neural cells in mice that are part of the olfactory system can detect unidentified alarm pheromones given off by other mice under stress. The scientists collected air from around stressed mice and then exposed other mice to it. Normal mice froze (a typical danger reaction in mice) when exposed to the alarm-pheromone scented air, whereas mice whose special olfactory neural cells had been destroyed did not respond to alarm-pheromone scented air at all.

It would be interesting to know whether humans also give off alarm pheromones. Could this be an explanation for why people seem to internalize the stress of others around them?

Thursday, August 21, 2008

Fatness, Fitness, and Health

Human Biology, 5th ed. (pp. 346-34) has a Current Issue feature on the topic of whether or not being “overweight” (BMI 25-30) is overstated as a risk factor for poor health or mortality. A report out just last week in The Archives of Internal Medicine (168: 1617-1624, 2008) supports that notion. The study documents the prevalence of six cardiometabolic risk factors (elevated blood pressure; elevated triglyceride level; decreased HDL level; elevated fasting glucose level; insulin resistance; systemic inflammation) in normal, overweight, and obese individuals. The study found that nearly 24% of all normal-weight individuals were ”metabolically abnormal” by virtue of having at least two of the six risk factors. And conversely, 54% of the overweight individuals were still metabolically healthy. The study suggests that just being overweight does not necessarily mean that an individual is at increased risk for heart disease.

A study published last December tends to support the hypothesis that being overweight is not as important a factor previously thought (Journal of the American Medical Association 298:2507-2516, December 5, 2007). In this study, 2603 adults over the age of 60 were tested for cardiovascular fitness (gentle treadmill test) and then mortality was followed for 12 years. Overweight individuals did have a higher mortality rate than did normal-weight individuals (18 vs 13 deaths per 1000 person-years). However, even more striking was the effect of fitness; mortality rate of the least-fit quintile was four times that of the most fit quintile (33 vs. 8 deaths per 1000 person-years.) Among the older generation at least, maintaining cardiorespiratory fitness may be more important than maintaining a normal body weight. Whether this is also true for younger individuals remains to be seen.

Wednesday, August 13, 2008

Testing Fingerprints for Illicit Substances

Could your fingerprints tell more about you than just who you are? A brief report in Science this month describes a technique that could allow crime investigators or even employers to analyze fingerprints for a variety of chemicals, including explosives and substances of abuse, such as cocaine. And since the chemicals would be determined from a single fingerprint, there would be no doubt as to who had handled the substances.

Law enforcement officials and crime investigators will welcome the technique as another weapon in their arsenal against crime. But the ability to test fingerprints for certain chemicals could also raise some privacy concerns for us all. Would we consider it ethical for an employer to enter workers’ offices to check for fingerprints containing traces of illegal drugs, without the employee’s knowledge or consent?

Reference: “Latent Fingerprint Chemical Imaging by Mass Spectrometry”. Science 321:805, August 8, 2008.

Sunday, August 10, 2008

A Daily Pill Against HIV Infection

First came the news that several AIDS vaccine trials had to be halted because the vaccines just didn’t work. Then last week the CDC admitted that number of people newly infected with HIV in the U.S. each year is nearly 40% higher than previously reported. Is there ANY good news on the AIDS front?

Well, yes…..maybe. A document released this month by the AIDS Vaccine Advocacy Coalition describes a potentially powerful new HIV prevention method called pre-exposure prophylaxis (PrEP.) It’s a simple notion, really – that a daily pill consisting of one or more of the current AIDS treatment drugs might prevent HIV infection from occurring in the first place. There are at least seven clinical trials of PrEP either planned or underway using the drugs tenofovir and emtricitabine, both of which are already approved for treating people who are currently HIV-positive.

No one knows for sure whether PrEP will work, but there are some promising signs that it might. But even if PrEP does prevent HIV infection, there would still be the issues of access and cost. In order to prevent HIV infection the drug would need to be available to a lot of healthy people, rather than just the few who are already infected.

A report on the status of PrEP research and some of the issues related to its use in AIDS prevention can be accessed at

Wednesday, August 6, 2008

HIV/AIDS Incidence Revised Upward

The number of new HIV infections per year in the United States has been grossly underestimated for the past 20 years, according to an article published in today’s Journal of the American Medical Association (“Estimation of HIV Incidence in the United States.” JAMA 300:520-529, August 6, 2008.) The new estimate for HIV incidence is 56,300 new cases in 2006, 40% higher than previously reported by the CDC. The new data also show that the incidence of HIV has not declined at all since 1991, in sharp contrast to the previously estimated 50% decline since that time (compare Figure 1 in the JAMA article with Figure 9.24 in Human Biology, 5th ed., taken from official CDC data available at the time.) The total number of people living with HIV/AIDS is also expected to be revised upward, but those numbers will not be available until later this year.

How could the numbers have been so far off? For one, the new data are based on better testing methods that more precisely differentiate new HIV infections from long-standing ones. In addition, HIV infection rates are notoriously hard to come by, especially back in time. Even the new estimates are based on extrapolations using data from only 22 states. The CDC does the best it can do with limited data; the rest is an educated estimate.

Officials emphasize that this does not mean that there actually were more new cases of HIV – rather, we now have better estimates of the actual rates of new infection that existed at the time, regardless of whether or not they were accounted for. Nevertheless, some Democrats are criticizing the Bush administration for not doing enough to combat HIV/aids in this country. Senator Waxman of California released a statement last week in which he pointed out that the CDC budget for prevention has actually shrunk by 19% since 2002, and that the president recently requested a reduction in funding for HIV prevention at the CDC. Given that the incidence of HIV has not declined at all over the past 15 years, Senator Waxman may have a valid concern.

Students may react with a "So what are we supposed to believe, when even scientists can't get it right?" attitude. They'll need convincing that this kind of "flip-flop", as it would derisively be labeled in politics, is actually a normal part of a healthy scientific process.

Monday, August 4, 2008

Enhancing Taste Sensations

Scientists at San Diego-based Senomyx are searching for compounds that specifically magnify just one of the taste sensations we especially prefer (sweet, salty, or savory) or that block the sensation of bitterness. After searching through tens of thousands of synthetic and natural compounds, they now have several specific “flavor modulator” compounds that appear to work.

The commercial possibilities and health implications are almost limitless. If food product manufacturers could use less sugar in their products and still satisfy our craving for that sweet taste, perhaps people would be able to diet more effectively. Caloric intake might decline, leading to a reversal of the obesity epidemic. Less salt in our food products might mean less cardiovascular disease. Block the bitter taste receptors and children would eat more vegetables. Bitter medicines would be more palatable, improving patient compliance in taking them.

Some big companies are interested, including Coca Cola, Nestle, and Cadbury. Nestle is already using a flavor modulator from Senomyx in some of its products. Read about it in this month's Scientific American (“Magnifying Taste.” Scientific American August, 2008, pp. 96-99.) You’re likely to see “flavor modulators” or “taste enhancers” listed among your favorite products’ ingredients in the near future.

Saturday, August 2, 2008

California Bans Trans Fats

The State of California has banned the use of trans fats in most food products. The ban goes into effect for all restaurant products in 2010 and for all retail baked goods in 2011. Packaged foods will not be affected, however.

Trans fats are created by bubbling hydrogen through liquid oil at high temperature. The resultant partially hydrogenated oil is a solid at room temperature. Trans fats prolong the shelf life and (some say) improve the flavor of foods. They were popular as a deep-frying oil until it became apparent that they raise the levels of low-density lipoproteins (the bad cholesterol), thereby potentially contributing to heart disease. Some restaurant chains, most notably McDonalds, have already discontinued the use of trans fats in their deep-fryers, and other chains are following suit.

The California ban raises an interesting question: Whose responsibility is it to legislate our health? The California Restaurant Association argued (unsuccessfully) that it should be the federal government, not the states – otherwise, restaurants with outlets in many states could face a wide array of different rules.

But if the government won’t act, should the states be allowed to? Until California’s law is challenged in federal courts, the answer is “Yes”. What do YOU think?

Sunday, July 27, 2008

Why We Believe Anecdotal Evidence

Why do many people persist in believing that certain vaccinations may cause autism, despite the fact that there has never been any scientific evidence to support such a claim? Why is it that we continue to be suckers for all kinds of vague, unsubstantiated health claims for various herbs and food supplements? Michael Shermer, publisher of Skeptic magazine, thinks he’s found a reason. He hypothesizes that our willingness to believe in anecdotal evidence over objective data is hard-wired into our brains as a consequence of evolution. He argues that making a false positive error (believing that "A" leads to "B" when actually it does not) usually has no consequences – if you believe that a fruit is poisonous, choosing not to eat it only leaves you hungry. On the other hand, making a false negative error (failing to believe that "A" leads to "B" when in fact it actually does) can kill you - if you eat a poisonous fruit you may die.

What do you think? Read Mr. Shermer’s one-page opinion column in the August issue of Scientific American (“Wheatgrass Juice and Folk Medicine”, Scientific American August 2008, p. 42) and judge for yourself. This article might be a useful supplement for Chapter 1, Human Biology, 5th ed.

Tuesday, July 22, 2008

Losing the Battle Against Bacteria

Bacterial resistance to antibiotics is increasing and there are too few new antibiotics in the drug discovery pipeline. Nevertheless, more than half of the major pharmaceutical companies have shut down their antibiotics R&D divisions entirely within the last 20 years. Read about it in the current issue of Science (“The Bacteria Fight Back”, Science 321:356-361, July 18, 2008). The article documents the history and the biology of bacterial resistance to antibiotics. It also and suggests some reasons why pharmaceutical companies seem disinterested in developing new antibiotics, even as the human death toll rises.

This would be a good article to share with your students in support of the Health Watch box on page 18 of Human Biology, 5th ed. The article could also be used to kick off a class discussion of the economics of developing and selling pharmaceutical drugs.

Sunday, July 20, 2008

Human Drugs From Plants

Remember Cerezyme, that very expensive drug that can cost patients up to $300,000 per year? (See this blog, March 17, 2008.) Cerezyme is a human enzyme called glucocerebrosidase. It is missing in patients with a rare genetic disorder called Gaucher’s disease, found mainly in persons of Ashkenazi Jewish descent.

There may be good news for Gaucher’s disease sufferers soon. An Israeli company named Protalix Biotherapeutics has developed a protocol for producing recombinant glucocerebrosidase cheaply in large amounts. But they’re not using animals – they’re using genetically engineered carrot cells grown in cell culture in big plastic bags. The enzyme is already in Phase III clinical trials, meaning that it is being tested in human patients. If approved by the FDA it will be the first plant-made recombinant drug ever approved for use in human patients. This could be a breakthrough that leads to a whole new field in drug development – making drugs by inserting human genes into plant cells.

To read more about it and see a photo of the carrot cells in culture, go to Protalix’s website at

Thursday, July 17, 2008

Dieting is Not Very Effective

Confirming what many dieters already know, most diets don’t work all that well over the long term. In a study that just came out today, over 300 moderately obese subjects (average Body Mass Index; 31) were placed on one of three different diets for two years. Participants lost 10-14 pounds within five months, but then they stopped losing weight and even gained some of the weight back over the next year and a half. At the end of a full two years, participants had lost only 6-10 pounds on average – not a lot, considering they were obese to start with.

The study’s authors most likely were disappointed (the study was funded in part by the Atkins Foundation, and a low-carb diet was one of the diets tested.) But based on some observed changes in lipid profiles, they suggest that the diets may have conferred some health benefits to the participants despite the minimal weight loss. It’s an interesting hypothesis, but it’s certainly not a valid conclusion at this point.

Reference: “Weight Loss with a Low-Carbohydrate, Mediterranean, or Low-Fat Diet”, The New England Journal of Medicine 359:229-241, July 17, 2008.

Tuesday, July 15, 2008

Paths of Human Migration

Scientists are now able to trace the routes taken by the ancestors of modern humans as they migrated out of Africa by tracking small changes in fossil DNA. The route maps are surprisingly complete - it almost seems as if prehistoric humans were walking on superhighways at super-slow speeds. In actual fact, they stopped and established colonies along the way, staying in one place for generations when conditions were right for human habitation. Modern humans finally reached South America roughly 40,000 years after their ancestors first left Africa - that's an average speed of less than 1/2 mile per year. The route took them across the Arabian peninsula, over Asia to Siberia, across a narrow land bridge to Alaska, and then south across North and Central America.

The techniques for tracing human migrations and the various routes taken are documented in “Traces of a Distant Past” (Scientific American, July 2008, pp. 56-63.) This would be a great paper to share with your students when you're discussing human evolution.

Sunday, July 13, 2008

Gardasil and Irresponsible Journalism

Last Monday the CBS Early Show ran a story about a 14-year-old girl named Jenny who is now nearly completely paralyzed by a degenerative mucle disease of unknown cause. It just so happens that she received Gardasil, the vaccine against human papillomavirus (HPV) 15 months ago, like so many other girls her age. Her parents spoke to CBS News with the hope that coverage of Jenny’s plight would help them find “comparables” - other patients with the same symptoms, so that her doctors could discern the actual cause of her disease. Nevertheless, CBS chose to run the online story with the more sensationalist headline, “HPV Vaccine Linked to Teen’s Paralysis?” (, July 7).

Four days later, FOX news went one step further with a story entitled “HPV Vaccine Blamed for Teen’s Paralysis” (, July 11).

This is biased journalism at its worst. Who exactly is blaming Gardasil for Jenny’s disease - Fox News? In fact the Fox News article is full of errors. For one, the article attributes to Jenny’s parents a statement made by a spokesperson for Merck, Gardasil’s manufacturer. In addition, the article uses the word “casually” in place of “causally”. For the record, what a Merck spokesperson actually said was, “We’re aware of this case and based on the facts that we’ve received, the information doesn’t suggest that this event was causally associated with vaccination.”

On their blog site on July 7 (see, the parents expressed disappointment with the CBS news coverage, saying “The family believes that there may be a link between Jenny’s health and the HPV vaccination……” “But, there is no medical consensus on whether this hypothesis is stronger than other possible explanations.”

Jenny’s parents are obviously scientifically literate. They know how to distinguish between a hypothesis and a scientifically justifiable conclusion. As you’re discussing the importance of being scientifically literate in your classroom, Jenny’s parents’ blog site and the two news articles would make interesting topics for discussion.

One final thought: Do you think that the biased news coverage of Gardasil could be intentional, given that conservatives don’t like the idea of a vaccine against a sexually transmitted disease being given to young girls? What do your students think?

Sunday, July 6, 2008

Your Cell Phone's Radiation Emission

Does the radiation emitted by cell phones cause brain cancers? Although most of the scientific evidence suggests that it doesn’t, the media always seems to find a physician or a patient or even a scientist who is willing to talk about it. The debate has been going on since cell phones first came out, and it’s not likely to go away any time soon.

Are you concerned? How much radiation does your cell phone emit, anyway – a lot, or a little? The Federal Trade Commission sets an upper limit of 1.6 W/kg (watts per kilogram) for certification, but commercial phones on the market vary all the way from 1.6 down to 0.14 – more than a 10-fold difference.

For a complete listing of the radiation output of all current phone models, go to, go to “Reviews - cell phones”, then click on “Cell phone radiation charts.”

Friday, June 27, 2008

Cell Phones and Brain Cancer

It happens over and over. First, someone says (again) that cell phones may cause brain cancer. Then the FDA reports that there is no convincing evidence that cell phones are a health risk. (See “Experts Revive Debate Over Cellphones and Cancer”, The New York Times online, June 3, 2008.) What’s a consumer to believe?

This is a good example of the limitations of the scientific method, and why it is sometimes hard to know the truth. Regarding the first statement, yes, cell phones may cause brain cancer (and then again, they may not.) As for the second statement, it is true that there is still no scientifically convincing evidence that cell phones are a health risk. (But again, that doesn’t mean they aren’t!)

Why is it so hard to find the truth? First, brain cancers are so rare that one would have to study literally hundreds of thousands of people. Second, to do the scientific study properly, a controlled study would need to be done in which the lives of hundreds of thousands of people would have to be strictly controlled. It can’t be done. Third, no one has used cell phones for 50 years, so potential long-term effects won’t show up for awhile. And fourth, modern phones emit much less energy than the older models did.

What can we do? We can study those few patients with brain cancer and ask questions – questions about health habits, including past cell phone use. Self-reports by patients are notoriously unreliable, of course, so it may take hundreds of such studies before we consider the evidence “convincing”. We don’t need to panic, but we need to be watchful of the changing state of knowledge regarding cell phones and cancer.

Incidentally, a similar question came up in the 1950s when smoking was actively encouraged – does smoking cause lung cancer? Who could have known that nearly sixty years later the rates of lung cancer in persons over 65 would be more than five times the rates of that same age group in 1950?! However, this does not imply in any way that the same sort of outcome is inevitable for cell phones. They're totally different issues.

Sunday, June 8, 2008

Your Bacterial Friends

How many bacteria normally live on or in your body, and what are they doing there? The government wants to know, with the goal of better understanding their roles in health and disease. So last year NIH launched the Human Microbiome Project. The early results show that bacteria and other microbes colonizing human tissues outnumber the body’s cells by ten to one! Over 600 different bacteria have been identified in such places as the vagina, belly button, nose, mouth, and digestive tract, not to mention all over the skin. And would it surprise you to know that there are more bacteria in your belly button than between your toes? Different bacteria influence our ability to fight infections, digest nutrients, and produce vitamins, plus there may be many other functions that we don’t even know about yet.

See the brief news article on this subject in Science magazine (“Bacteria are Picky About Their Homes on Human Skin”, Science May 23, 2008, p. 1001.)

Saturday, June 7, 2008

What Defines a Species?

That question confuses even the experts. Even Darwin couldn’t do it. In 1856 he wrote, concerning the definition of species, “It all comes, I believe, from trying to define the indefinable”.

Traditionally, biologists loosely define a species as a population whose members breed mostly among themselves under natural conditions. Generally this means that they are genetically distinct. But now that we can sequence DNA, the concept of “genetically distinct” itself is problematic - exactly how many genes or base pairs have to be different? As one species evolves to become two, when are they different enough? It’s not just a philosophical exercise; how a particular species (or group of individuals within a species) is defined may determine whether it is an “endangered species” or not, and thus worthy of protection under the law. It can mean its very survival.

For a good recent article on the subject, see “What is a Species?”, Scientific American, June 2008, pp. 72-79.

Monday, June 2, 2008

GINA Finally Passes

After thirteen years of wrangling and a failed attempt last year (see this blog, May 8, 2007), Congress finally passed the long-awaited Genetic Information Nondiscrimination Act (GINA). President Bush signed it into law on May 21, 2008.

GINA makes it illegal for health insurers to deny coverage or raise premiums based on genetic information. It also prohibits employers from using genetic information in making decisions regarding job assignments, promotion, hiring, or firing. Patients and health care workers had been pushing for the bill for years, claiming that people were afraid to take genetic tests, such as the one for the breast cancer genes BRCA1 and BRCA2, because they were afraid of being denied insurance coverage or a job should they test positive.

Why did it take so long for the bill to pass? Some lawmakers, most notably Senator Tom Coburn of Oklahoma, were worried that the bill would create a windfall for trial lawyers as people sued insurance companies and employers over alleged discrimination in health care coverage. The final bill addresses that question to everyone’s satisfaction, apparently.

Sunday, June 1, 2008

Teens and Energy Drinks

There’s growing concern among school officials and health care workers that teen use of energy drinks such as Red Bull and Spike Shooter are early warning signs of the willingness to take risks. According to researchers, high consumption of energy drinks is associated with aggressive and risky behaviors, including substance abuse, violence, and unprotected sex. No one is saying yet that these energy drinks cause such behaviors, but parents should probably be aware that teens who are willing to abuse caffeine may be more likely to engage in other risky behaviors as well. The research is published in the March issue of The Journal of American College Health and discussed in a recent news article (“Taste for Quick Boost Tied to Taste for Risk”, New York Times online May 27, 2008.)

The energy drink Spike Shooter contains 428 mg of caffeine in 12 ounces, or about 12x that of Coke or Pepsi and 2-5 times that in a cup of coffee. Teens have been sent to the emergency room with heart palpitations, jittery behavior, and sweating as a result of drinking too many energy drinks. Some teens are combining these drinks with alcohol in the mistaken belief that it makes them less drunk.

Do your students use energy drinks, and do they know what's in them?

Wednesday, May 28, 2008

Global Warming and U.S. Precipitation

A new government report predicts that in the next 50 years there will be significant shifts in precipitation across the United States as a result of increased carbon dioxide in the atmosphere. The report predicts that the arid Southwest and West, already struggling with chronic water shortages, will become even drier. In contrast, parts of the Northeast and East will experience up to 20% more precipitation, leading to increased runoff in streams and rivers. These changes are likely to disrupt water supplies, affect agricultural and forest productivity, and alter ecosystems.

So it’s not just a rising average temperature that we have to worry about with global warming; shifting weather patterns are likely to be just as disruptive. See “Synthesis and Assessment Product 4.3 (SAP 4.3): The Effects of Climate Change on Agriculture, Land Resources, Water Resources, and Biodiversity in the United States”, at

Friday, May 23, 2008

Pet Cloning Goes Commercial

A California biotech company called BioArts plans to hold a public auction to clone five dogs. The scientist involved in the actual cloning will be the South Korean researcher who cloned Snuppy, the male Afghan hound pictured in Human Biology, 5th ed. (p. 418), and who later claimed (fraudulently) to have cloned human embryos.

The auction will be held July 5th through 9th online, with bidding to start at $100,000. The company promises the buyer a puppy that resembles the original dog, guaranteed healthy for a year. The company says that the success rate with cloning dogs has improved to the point that 25% of all embryo transfers now result in a puppy, and that the puppy survival rate is 80%.

Human cloning can’t be far behind. The sticking point is the success rate and the health of the clone – do we really think that a survival rate on the order of 80% would be worth the risk? No one knows the long-term health risks.

Monday, May 19, 2008

From Sewage to Drinking Water

Los Angeles officials are proposing to recycle heavily treated sewage water back into the ground. The water would eventually make its way into the aquifers that supply drinking water to the city (“Los Angeles Eyes Sewage as a Source of Water”, LA Times May 15, 2008). The plan is understandably controversial, with some residents complaining that it should be put to a vote rather than decided upon by city officials.

A similar plan was abandoned in the 1990s after a public campaign was mounted against it. But this time around the critics seem to be less vocal, in part because the chronic water shortage in LA is predicted to only get worse and in part because the technology for cleaning up sewage water keeps getting better and better.

It might be interesting to ask your students if they would vote for such a plan in their community, or ask them what THEY would see as the best way to solve a water shortage problem. You could also ask them to look into and report on current techniques for treating sewage water.

Saturday, May 10, 2008

Fat Cells are Replaced Throughout Life

It is known that every adult has a relatively constant number of fat cells - obese people just tend to have more of them than thin people. When we gain or lose weight our fat cells swell or shrink, but the number of fat cells stays the same. This is one reason why it is so hard for some obese people to lose weight; they are constantly fighting internal homeostatic mechanisms that work to maintain their fat cell's "normal" weight.

But now, researchers have discovered that although you do have a constant number of fat cells throughout life, they are not the same cells. About 10% of them die each year and are replaced by new ones.

No one knows for sure what determines how many fat cells each person has. But the findings open up interesting new avenues for weight control research. If we could determine what regulates the number of fat cells and then alter that regulation, or if we could slow the rate of fat cell division, we might have a new way to fight obesity.

Monday, May 5, 2008

Texas Blocks 'Creation Science' Master's Degree

The Texas Higher Education Coordinating Board voted unanimously last month not allow the Institute for Creation Research (ICR) to grant online Master of Science degrees in science education. The ICR makes no secret of the fact that it supports a literal interpretation of the Bible, including the creation of Earth in six days.

“Religious belief is not science,” said the state’s commissioner of Higher education in recommending to the board that they disallow the ICR application. He added, “Science and religious belief are surely reconcilable, but they are not the same thing.”

Wednesday, April 30, 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.

Monday, April 28, 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.

Wednesday, April 23, 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 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.

Monday, April 7, 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.

Thursday, April 3, 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”,

Tuesday, April 1, 2008

Speedier Speedos

Can a swimsuit make you go faster in the water? Will athletes be willing to pay more than $500 for one? Speedo is betting that the answer to both questions is “yes”. Its new high-tech Speedo LZR Racer is designed to do for swimming what titanium golf clubs and carbon composite rackets did for golf and tennis, respectively. And it might do just that!

The new suit has no stitching; the parts are all bonded ultrasonically. Low-drag panels are incorporated into the nearly complete body suit to compress the swimmer’s body. According to the company, the new suits have 5% less drag than older models. Critics argue that a suit doesn’t make a world-class swimmer, and of course on one level they’re right. On the other hand, in the past two months 14 new world records have been set in swimming – 13 of them in the LZR suit.

Expect to see the new suit all over the Olympics swimming competitions this summer.

Sunday, March 30, 2008

Oldest Pre-Human Ancestors in Europe

According to the cover story in Nature this week, a jawbone discovered in a cave in Spain pushes back the date of arrival of pre-human hominids in Western Europe to 1.1 million years. The jawbone belonged to a pre-human ancestor called Homo antecessor who lived approximately 300,000 years before the previous earliest-known pre-human in Western Europe. Artifacts at the site indicate that Homo antecessor fashioned crude tools and used them to butcher small animals.

We don’t mention Homo antecessor in Human Biology, 5th ed. so that the beginning student is not baffled by the number of pre-human hominid names that have cropped up in recent years. Until more fossils are discovered, it might be best to lump Homo antecessor with other better-known European archaic humans such as Homo heidelbergensis.

Reference: “The First Hominin of Europe”. Nature 452: 465-469, March 27, 2008.

Monday, March 17, 2008

A REALLY Costly Drug

A drug called Cerezyme has become a topic of debate among health care professionals, insurance companies, and patients. That’s because at the recommended dosage, the drug costs up to $300,000 a year.

Cerezyme is used to treat a rare inherited disorder called Gaucher disease, characterized by severe deterioration of bones and joints. The recommended dosage was determined on the basis of a clinical trial in only twelve patients more than 20 years ago. At the recommended dosage the drug has proven to be quite effective. But would a lower dose work just as well? Many doctors and insurance companies think so, but the manufacturer (Genzyme) has no interest in finding out. And why would they, when the drug has annual sales of over a billion dollars? Genzyme says it’s not their issue; they’d leave it up to doctors to determine whether a lesser dose would work just as well in their patients.

If the drug were cheap, dosage wouldn’t be an issue. But insurance companies are paying for this drug, and therefore so are we, indirectly. Who do you think should be responsible for determining the proper dose?

Thursday, March 13, 2008

Do Identical Twins Have Identical DNA?

It has long been thought that identical twins must have identical DNA, since they came from the same fertilized egg. The usual explanation for any observed differences between identical twins was that they were caused by environmental factors such as diet, exercise, or exposure to chemicals.

Now we know that the DNA of identical twins is not always identical. That's because as cells divide over and over again during normal human growth and development, some sections of the DNA are omitted accidentally once in awhile. Other sections of the DNA are duplicated unnecessarily. The result is that some somatic cells and even tissues and whole organs may have one to three copies of some genes, instead of the usual two. Such copy number variations occur rarely in all people, not just in identical twins.

It would be helpful to know whether copy number variations contribute to specific human diseases, and (out of curiosity) whether copy number variations contribute to the slightly different phenotypes of some "identical" twins.

Monday, March 10, 2008

Inhaled Insulin (Who Cares?)

Eli Lilly & Company announced that it was halting development of its inhaled insulin product because it no longer believes that the product has sufficient market potential. The company recorded a three-month loss of $90–120 million to shut down the failed project. The announcement comes just five months after the first inhaled insulin product, Pfizer’s Exubera, was pulled from the market because of weak sales.

What happened? For decades, scientists and drug marketers dreamed of blockbuster profits from the first inhalable insulin product that would eliminate the need for injections in the treatment of diabetes. It turns out that no one cared. Patients didn’t like the cumbersome device used to administer the powdered insulin, and doctors found that the powders had a slight tendency to impair lung function.

It seemed like such a good idea.

Saturday, March 8, 2008

Hormone Replacement Therapy Revisited

Back in the 1990s the federal government launched the Women’s Health Initiative to investigate the health of older women. One of its goals was to determine the risks and benefits of hormone replacement therapy (HRT) in post-menopausal women. The HRT study was stopped early (in 2002) when it was discovered that HRT led to an increased risk of breast cancer, heart attacks, and strokes.

What about the women who were on HRT during the study - do they remain at higher risk even after discontinuing HRT? The good news is that apparently most of the increased risk goes away with time. The first follow-up study indicates that three years after HRT is discontinued, the increased risk of heart attacks disappears, and the increased risk of cancer declines significantly. Future reports will show whether any increased risk of cancer remains as time passes.

Current recommendations for HRT remain unchanged; women should consider HRT only if they have moderate to severe post-menopausal symptoms, and for the shortest time and lowest dose that is effective.

Monday, March 3, 2008

Global Warming and Science Literacy

If people really understood global warming they’d be more concerned about it, right? Wrong! According to a recent survey, respondents who are more informed about global warming and who have a high confidence in scientists “feel less responsible for global warming, and also show less concern for global warming” (Personal Efficacy, the Information Environment, and Attitudes Toward Global Warming and Climate Change in the United States. Risk Analysis 28:113-1267, 2008).

Why is that? The authors suggest that its because “Global warming is an extreme collective action dilemma, with the actions of one person having a negligible effect in the aggregate.” They suggest that because informed persons understand this, they tend to feel less personally responsible and more pessimistic about their ability as individuals to change the outcome.

Okay, informed persons may feel less responsible, but why are they less concerned? One possible explanation is that people who are informed about science tend to trust that scientists will find a technological solution. After all, we’ve sent men to the moon, discovered antibiotics, and developed computers, haven’t we?

How confident are your students that scientists will find technological solutions to global warming in their lifetimes? Do they see any technological solutions on the horizon?

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.

Wednesday, January 30, 2008

Creating Synthetic Life

Scientists at the J. Craig Venter Institute in Rockville, Md. have succeeded in synthesizing the entire genome of the bacterium Mycoplasma genitalium, using only the four nucleotides of which all DNA is comprised. It’s an astonishing feat, considering that the M. genitalium genome is nearly 600,000 base pairs long. The next step, say the researchers, is to insert the synthetic DNA into a cell. If all goes well, the DNA will replicate itself and the cell will divide, becoming the first living, self-reproducing organism ever created synthetically in a laboratory.

The synthesis of the entire genome of an organism paves the way for experiments to determine the minimum number of genes required for life – the minimum operating system, so to speak. Looking further to the future, someday it may even be possible to create synthetic organisms for specific purposes, such as manufacturing medicines or cleaning up the environment. We’d better start thinking about how we want to regulate or control this new technology.

Monday, January 14, 2008

A Beating Heart is Created in the Laboratory

University of Minnesota researchers have succeeded in producing a beating rat heart in the laboratory. In their experiments, the researchers first removed all the heart cells from a dead rat heart by dissolving them away with a strong detergent, leaving just a scaffold of connective tissue and heart valves. Then they infused cells harvested from the heart of a newborn rat. Within two weeks a new beating heart developed.

The research marks a significant advance in our understanding of what it would take to grow human hearts. However, scientists caution that the ability to produce human hearts for implantation still may be decades away. First, it will have to be shown that the technique can be adapted to larger animals. And second, methods will have to be developed to create the hearts from stem cells rather than cells from a newborn. Obviously, no one would sacrifice a human newborn just to produce a new heart for an adult!

Nevertheless, this is an encouraging first step.

Saturday, January 12, 2008

AIDS proteins

The AIDS virus can only make about 15 proteins on its own. In order to reproduce, it must rely on its ability to force its human host cell to make all of the other proteins it needs.  And with the use of a new genetic screen, researchers at Harvard University have identified at least 273 of these human proteins.  Knowing precisely which human proteins the virus needs may lead to techniques for growing the virus in the laboratory for research purposes, or ways to block one or more of these key proteins in humans without disrupting the human body very much.

Instructors who are especially interested in how viruses reproduce may wish to read the full research article (Science online January 10; "Identification of Host Proteins Required for HIV Infection Through a Functional Genomic Screen") and comment on its findings in class.   The article itself is too difficult for entry-level students. 

Friday, January 11, 2008

Thimerosal and Autism

The results of a study by researchers at the Department of Public Health in California do not support the hypothesis that autism is caused by thimerosal, a preservative containing ethylmercury that was once used in childhood vaccines. The researchers found that the incidence of autism rose steadily in California from 1995 to 2007, even though thimerosal was removed from most childhood vaccines in 2001. If thimerosal were responsible for causing autism there should have been a sharp decline in new cases of autism after 2004. The new findings and a commentary about them are published in The Archives of General Psychiatry.

It is doubtful that the study will do much to reassure parents, however, some of whom continue to believe passionately that their child's autism was a direct consequence of childhood vaccinations despite research findings to the contrary.

Thursday, January 3, 2008

The Limits of Science

The free online version of the New York Times has a recent article that could be used to start a discussion in your Human Biology classroom about the limits of science. (“Both Sides Cite Science to Address Altered Corn”, Dec. 26, 2007, In this case, Europeans are arguing over whether or not to ban the planting of a pest-resistant strain of genetically modified (GM) corn.

Interestingly, both sides are trying to justify their position on the basis of science. Those opposing the planting of the GM corn argue that one can never be absolutely certain that the new corn is completely safe. They are right, of course; science cannot absolutely prove GM corn’s safety under all known (and as yet unknown!) conditions. On the other hand, those in favor of planting the GM corn argue that according to the currently available scientific evidence, GM corn is “unlikely” to pose a significant risk. They are right, too.

Ultimately, the decision of whether or not to ban GM corn will be a public policy decision based not only on the available scientific data, but also on political, economic, and social pressures. Nevertheless, science certainly does have an important role in issues such as this. Points of concern raised during public debate can perhaps be tested by science, improving our confidence in public policy decisions both now and in the future.