Sunday, December 27, 2009

Who Were the Hobbits' Ancestors?

In 2004 scientists unearthed a partial skeleton and other bones on the island of Flores in Indonesia. The scientists postulated that the skeleton belonged to an extinct species of primitive humans that had descended from Homo erectus ancestors. They named the new species Homo floresiensis, but the press dubbed them the hobbits because of their diminutive size.

Almost immediately the new find created a controversy. If Homo floresiensis descended from the much larger Homo erectus, how did they come to be so small, and in particular, how did their brains become smaller, too? Some scientists postulated that the skeleton was just a diseased modern human; others argued that the new species had undergone a phenomenon known as “island dwarfing”.

Analysis of the morphological features of Homo floresiensis has led to a new theory, summarized recently by Kate Wong in Scientific American – that Homo floresiensis descended not from Homo erectus, but from older (and smaller) ancestors, such as Homo habilis. That would explain LB1’s small size and diminutive brain, but it raises more questions than it answers. For example, if Homo floresiensis diverged from other known human lines nearly two million years ago, why haven’t other skeletons of this species been found? Did Homo floresiensis emigrate from Africa even before Homo erectus did? Where did they go before arriving in Indonesia?

It’ll be interesting to see how our thinking about Homo floresiensis evolves as new information comes in.

Reference: Wong, Kate. Rethinking the Hobbits of Indonesia. Scientific American, Nov. 2009, pp. 66-73.

Monday, December 14, 2009

That's One Small Step for Gene Therapy...

French researchers report that they have successfully used gene therapy to treat beta-thalassemia in a 19-year-old male patient. Beta-thalassemia is a genetic blood disorder in which a defect in the gene coding for the beta-globin chain of hemoglobin results in persistent and life-threatening anemia and dangerously high blood iron levels. Two years after the treatment, according to the researchers, the young man no longer needs regular monthly blood transfusions and appears to be in good health.

The French team has the approval of French authorities to treat more patients with the same inherited disorder. The hope is that someday they’ll be able to successfully treat one of the most common of all genetic blood disorders – sickle cell anemia.

Saturday, December 12, 2009

H1N1 Flu Deaths Update

The Centers for Disease Control and Prevention estimated this week that between 7,000 and 14,000 people have died of swine flu in the U.S. through mid-November, out of the 34-67 million people who had the swine flu so far.

Deaths caused by the flu are notoriously hard to estimate because most people are not tested for the flu when they have it and because people may die of a combination of causes, including the flu. The usual estimate is that the regular seasonal flu causes about 30,000 deaths each flu season (the winter months), so these latest swine flu numbers aren’t too bad. In fact they’re well below the government’s estimate back in August of 30,000 to 90,000 deaths from swine flu this season.

The big question is what will happen in January/February – will swine flu reassert itself in a third wave, as happened in the pandemics of 1918 and 1957? Will the H1N1 virus change to become more lethal, or more resistant to the vaccine? If either of these things happens the situation could change quickly. Most people in the U.S. are not yet immune to the swine flu because they have not had it yet and they have not been vaccinated against it.

Apparently many people think the danger is passed. We’ll hope they’re right. But if you still haven’t gotten your swine flu shot, it’s not too late. The vaccine supply seems to be pretty good these days.

Thursday, December 10, 2009

Prion-like Activity in Neurodegenerative Disorders

Could misfolded human proteins with prion-like activity contribute to the progression of certain chronic diseases such as Alzheimer’s, Parkinsons, and Huntington’s disease? A common feature of all three of these diseases is the presence of abnormal accumulations of certain misfolded proteins in or around nerve cells in the brain. Eventually these protein accumulations become so extensive that they choke off nerve cell function.

No one is saying that these diseases are infectious, like mad cow disease. But according to the latest thinking, once an endogenous protein "goes rogue" and misfolds, it might then cause nearby normal proteins to misfold as well. Once the process starts it could become self-propagating, from one region of the brain to the next.

Wednesday, November 25, 2009

Breast Self Examination

Women; have you been feeling guilty because you haven’t been doing regular breast self-examinations to make sure you aren't developing breast cancer? Well, here’s good news for you. The U.S. Preventive Services Task Force (USPSTF), which makes recommendations about preventive care services for people who do not yet have any signs or symptoms of disease, is now recommending against breast self-examination (BSE) as a way to detect breast cancer. (The USPSTF’s previous position on the usefulness of BSE was “insufficient evidence” either for or against).

The USPSTF systematically reviews of the benefits and harms of a preventive care services, and then tries to come up with a net assessment. In the case of BSE, the USPSTF reviewed the latest published data and concluded that; a) regular BSE does not lower the mortality rate from breast cancer, and b) women who perform BSE tend to have more imaging procedures and biopsies than women who don’t. These procedures are expensive and are themselves associated with minor health risks, such as infection and increased exposure to radiation. Overall, the net risk/benefit ratio for BSE is on the side of net risk.

The recommendation against BSE is only for women who are not at increased risk for breast cancer. Women who are at increased risk should consult their physician.

Reference: U.S. Preventive Task Force. Screening for Breast Cancer: U.S. Preventive Services Task Force Recommendation Statement. Ann. Int. Med. 151:716-726, 2009.

Saturday, November 21, 2009

Stress Reduction and Heart Attacks

It has long been suspected that a risk factor for heart attacks, in addition to lack of exercise, poor diet, high cholesterol, genetic makeup, and so on, is the level of stress in one’s life. Scientists have hypothesized for years that relaxation techniques such as yoga and meditation might have a positive effect on disease outcome, but it’s been difficult to prove.

Now a team of researchers claims to have proved it, according to a news article. They report that just 20 minutes of transcendental meditation per day significantly lowers the risk of heart attack by 47% in a group of high-risk patients (African American patients with narrowed coronary arteries.)

The results have not yet been published in a peer reviewed medical journal, the point at which they generally are accepted by the scientific community. Personally, I’d feel better if one of the researchers were not from the Maharishi University of Management, an institution founded by the Indian guru who popularized transcendental meditation back in the 1960s. In addition, it’s not clear whether the results in this one group of high-risk patients would translate to other types of high-risk patients, or to persons at lower risk. Time will tell whether the findings can be duplicated by other researchers and whether other stress relaxation techniques have a similar effect.

Sunday, November 15, 2009

Caffeinated Alcoholic Beverages Under Scrutiny

This week the Food and Drug Administration (FDA) notified 27 manufacturers of caffeinated alcoholic beverages that they must either explain to the FDA why they believe that the addition of caffeine to alcoholic beverages is “generally recognized as safe” (GRAS) or take their products off the market. According to the FDA, for caffeine to be allowed as an additive to an alcoholic beverage “there must be evidence of its safety at the levels used and a basis to conclude that this evidence is generally known and accepted by qualified experts.” If the companies cannot provide such data within 30 days, the FDA will “take appropriate action” to ensure that the products are taken off the market.

Caffeinated alcoholic beverages are marketed primarily to young people under such names as Max Vibe, Torque, and Evil Eye. Some promotional campaigns depict consumption of multiple drinks in conjunction with high-risk sports such as snowboarding and motocross biking. The action by the FDA comes after the agency received a letter from 18 state Attorneys General asking that the FDA use its authority to see that the products are removed from the market. The Attorneys General argue that caffeine can mask the effects of alcohol and could lead to increased risk-taking behavior.

The two largest manufacturers have already agreed to remove their products from the marketplace. It would not be surprising to see the others follow suit within 30 days.

Saturday, November 14, 2009

Energy Sustainability in 20 years?

Would it be possible to get 100% of our energy needs from renewable resources such as wind, water, and the sun in just 20 years? In theory, yes, but for practical reasons it's not likely to happen that soon. With current technologies it would require almost 4 million wind turbines, nearly 90,000 concentrated solar and photovoltaic power plants, and rooftop photovoltaic systems on nearly every rooftop – 1.7 billion, to be exact. Other challenges include a projected critical shortage of certain materials that would be needed, including rare earth metals (found primarily in China), lithium for lithium-ion batteries (half of the world’s reserves are in Bolivia and Chile) and platinum for fuel cells. In addition, we’d have to shift to shift to electric vehicles for transportation.

Fortunately, the technologies for harnessing energy from renewable resources continue to improve each year. It may take some time and effort, but what choice do we have? At current rates of consumption, known reserves of the non-renewable energy resources (coal, oil, and gas) will run out in less than a century.

Reference: Jacobson, Mark Z. and Mark A. Delucchi. A Path to Sustainable Energy by 2030. Scientific American pp. 58-65, Nov. 2009.

Monday, November 9, 2009

I Don't Hear You...

How does the public respond when a published scientific report shows that a dietary supplement is ineffective, or even worse, potentially harmful? To find out, scientists at the National Institutes of Health examined the sales trends of five different dietary supplements before and after the publication of negative research results. There were no significant declines in sales for four of the five supplements (saw palmetto, Echinacea, glucosamine, and St. John’s wort) after published reports that the supplement was ineffective. But sales of the fifth supplement (Vitamin E) declined about 33% after a report suggested that high doses of Vitamin E might actually be harmful.

Why did consumers ignore the reports that supplements just didn’t work, but responded to a report of potential harm? Researchers speculate that reports of harm might have higher impact because of greater news coverage, or that some supplements (such as Vitamin E) might be recommended more often by physicians who are more likely to read and understand scientific reports, or even that it depends on the type of person who takes a particular kind of supplement, the purpose of the supplement, and the availability of alternatives.

Still, it must be discouraging for public health officials to learn that consumers aren’t getting the message, don’t believe the message, or just don’t care whether their supplements work or not.

Wednesday, November 4, 2009

Water versus Ethanol

In 2007 the U.S. Congress passed the Energy Independence and Security Act, which calls for a five-fold increase in fuel-grade ethanol production by 2022. Most of the ethanol would come from corn produced in the Corn Belt states of the Midwest. It sounds good for the economy of those states, but there’s a catch; growing the corn and producing the ethanol would require nearly 100 gallons of water per gallon of ethanol, by some estimates. Eventually we might have to choose between water and ethanol, or between ethanol and higher food prices.

There would be winners and losers in an ethanol-based biofuels economy, because water generally must be used locally, whereas ethanol is more easily transported. Agricultural communities with plenty of irrigation water and the ability to grow corn would benefit from an ethanol-based biofuel economy. Agricultural communities with marginal water supplies would be forced to choose how best to use their dwindling water supplies – for agriculture or for people? City dwellers generally would be in favor of ethanol production for fuel by others; they don’t use much water for agriculture anyway and so have nothing to give up. However, they are likely to react negatively to a run-up in food prices.

What do you think about producing ethanol from corn?

Saturday, October 24, 2009

Infertility Patients Favor Stem Cell Research

Most couples that have had to resort to in vitro fertilization (IVF) techniques in order to have a child are in favor of stem cell research. When asked in a national survey what they might choose to do with their frozen embryos left over after they have successfully had a child, 60% reported that they were “somewhat likely” or “very likely” to donate them for stem cell research. In contrast, less than a quarter of the respondents planned to discard their frozen embryos, or expressed a desire to donate them to another couple.

Infertility patients are especially aware of the advances in science that have made it possible for them to have children. Perhaps they are just more grateful than most, but apparently most of them have resolved any internal moral dilemma over what to do with their leftover embryos. It is interesting, however, that most of them would rather donate their embryos to research than to know that their biological child was being raised by another couple.

Thursday, October 22, 2009

Phosphate Recovery From Sewage

In this blog (see "Dwindling Phosphorus Supplies") I talked about the world’s dwindling phosphate supplies, and how the key to sustainability of phosphate supplies would be recycling. But who among us has even thought about how we might recycle the gram and a half of precious phosphate we excrete in urine every day?

Well, a researcher at the University of British Columbia did, and then he set out to do something about it. Today, a phosphate recovery system based on his design is producing about a ton of slow-release phosphate fertilizer every day from a sewage treatment facility serving Portland, Oregon. The fertilizer is in such high demand that the recovery system will pay for itself in less than five years. Other recovery plants are planned, including larger ones to recover the waste from dairy and pig farms.

So if you live in Portland, Oregon, count yourself lucky; you already ARE recycling your phosphate! (Or at least somebody is.)

Reference: Tweed, Katherine. Sewage’s Cash Crop. Scientific American Nov. 2009, p. 28.

Monday, October 19, 2009

Tasting the Bubbles

It used to be assumed that the tingling sensation of carbonated beverages was due to stimulation of mechanoreceptors by bursting bubbles of CO2. In fact, researchers now know that we also have chemoreceptors for CO2, and that they are located on the same taste cells that detect sour taste. The receptor molecule is the enzyme carbonic anhydrase, which converts CO2 (plus a water molecule) into bicarbonate and a proton. Protons activate the taste cell, which in turn activates the sensory neuron that synapses with it.

Why don’t carbonated beverages taste sour, given that the carbonic anhydrase is located on the sour-detecting taste cells? No one knows for sure, but researchers speculate that the brain interprets CO2 receptor activation plus mechanoreceptor stimulation as primarily a tingling sensation.

Saturday, October 17, 2009

Stem Cell Therapy for Parkinson's?

Researchers in Europe are about to begin a long and expensive series of experiments to determine if transplantation of fetal brain cells into the brains of patients with Parkinson’s disease will improve the patients’ condition. The study is raising some eyebrows in scientific quarters. Two similar experiments carried out in the U.S. in the 1990s, admittedly when the techniques were less well developed, failed miserably.

If they get final approval to go ahead, the researchers will harvest fetal brain cells from 6-9-week-old human fetuses and then inject the cells into the brains of patients with Parkinson’s disease. Up to six fetuses will be needed to obtain the 8 million cells to be transplanted into each Parkinson’s patient, according to a news article in Science. The first patients will receive the injections in 2012 as part of a safety study. If all goes well, a double-blind trial complete with sham surgeries will be carried out to see if the procedure actually benefits patients.

Controversial? Yes. Worthwhile? You decide.

Sunday, October 4, 2009

Oldest Known Human Ancestor

In the October 2, 2009 issue of Science, scientists report on the discovery and reconstruction of the oldest known nearly complete skeleton of a female pre-human ancestor. Named Ardipithecus ramidus, “Ardi” stood only four feet tall and weighed about 110 pounds. Apparently she was a “facultative” biped, meaning that she could walk upright on the ground but was still able to climb and walk in trees.

The first bones of Ardipithecus ramidus were discovered in 1992, but it has taken this long to find and reconstruct enough of a skeleton to be confident enough to publish the results. And the results are stunning. At 4.4 million years old, Ardi pushes back the dawn of bipedalism by more than a million years. (“Lucy”, the celebrated Australopithecus afarensis shown on p. 518 of Human Biology, 5th ed., is 3.2 million years old).

It’s the biggest find in decades. You can find 11 scientific articles on Ardipithecus ramidus in Science online. For a summary, read the Perspectives article by Ann Gibbons entitled “A new kind of ancestor: Ardipithecus unveiled”.

Saturday, October 3, 2009

Encouraging Organ Donations

Fewer than 40% of all adults have signed a donor card or other legal document indicating their willingness to donate their organs after death. Perhaps it’s a form of avoidance, but for whatever reason we just don’t seem to get around to it. "Presumed consent" laws are one solution, but some people find presumed consent laws objectionable on the grounds that they are a form of religious discrimination. Under presumed consent, it's people who do not wish to donate (perhaps for religious reasons) who must make their wishes known in advance, not the other way around.

One innovative and eminently fair solution is to require everyone to make their wishes known. Its called “mandated choice”. In the State of Illinois, every person over the age of 18 who renews a driver’s license must answer the question, “Do you wish to be an organ donor?” The state now has a donor signup rate of 60%. Several other states (Pennsylvania, for one) ask the question as well, but it's for informational purposes only. In Illinois, the answer is considered legally binding, meaning that relatives cannot later overturn it.

Thursday, September 24, 2009

Fight Over Biotech Beets

Back in 2005, the U.S. Department of Agriculture conducted an environmental assessment of sugar beets that had been genetically engineered to resist the herbicide Roundup. They concluded that the new beets would have “no significant impact” on the environment, and therefore a full environmental impact statement would not be required. With that ruling, the beets were approved for widespread planting.

The new beets have been popular with farmers, and plantings have soared. But watchdog groups like the Center for Food Safety are not convinced that the Department of Agriculture should have approved the new beets so quickly. They have challenged the Department of Agriculture in court, and recently they won the first round; a Federal District Court judge in San Francisco has ruled that the Agriculture Department should have done an environmental impact statement before approving the beets for widespread planting. The judge in the case will decide on the correct course of action next month. But the plaintiffs have already said they would ask for a total ban on the biotech beets, according to an article in the New York Times this week.

Most consumers don’t seem to care; sugar is sugar.

Wednesday, September 16, 2009

Dwindling Arctic Sea Ice

The summer of 2009 marked an historic first; the first time that ships traveled from Asia to Europe via the Arctic Ocean. A short route from Europe to Asia has been the dream of sailors since Columbus set sail for Southeast Asia from Europe over 500 years ago. Two ships completed the first trip via the Arctic route in September of 2009, according to a news article on the Web site of the German shipping company, Beluga Shipping GmbH.

In 2009 there was only a short window of opportunity before sea ice closed the route again for the year. But in 30 years the trans-Arctic shipping season could last for three months or more. The new Arctic route cuts nearly 40% off the distance traveled via the usual more southerly routes through either the Suez canal or the Panama canal.

Global warming, dwindling sea ice; good for shipping, bad for polar bears.

Tuesday, September 15, 2009

Glucose Monitoring Devices are Inaccurate

Most diabetic patients measure their blood glucose level on a regular basis, as part of a daily regimen to try to maintain their blood glucose within normal limits. Many diabetics rely on home glucose monitors that are relatively cheap and easy to use - trouble is, they’re not very accurate. For example, one study reported that five different popular home glucose monitors gave readings that were different by as much as 30%.

Consumers probably are not aware that the devices can be this inaccurate. The Food and Drug Administration (FDA) is understandably concerned, and it’s pressuring the international organization that sets standards for the devices to tighten up the standards - or else the FDA may do it for them.

But this raises an interesting dilemma. Re-engineering and manufacturing the devices would make them more accurate, but it could also increase their price – at least, that’s the manufacturer’s arguments against new standards for accuracy. And if an increase in price caused some people to stop using them altogether, have we really gained anything? There’s always a trade-off; always a choice to be made…..

Friday, September 11, 2009

Treating "pre-osteoporosis"

First the definition of “overweight” was changed, making 35 million more Americans overweight overnight. Then normal blood pressure was redefined, and everyone just above it became “pre-hypertensive”. And now, millions of women with a bone density just slightly below normal (for a 30-year-old!) are being told they have a condition called “pre-osteoporosis”, or “osteopenia”. This is like telling a middle-aged woman she has a skin disease because her skin is not as smooth as her daughter’s. In fact, a woman’s bone density normally declines with age – its just part of the aging process. Bone density declines very slowly after 30 but before menopause, and then accelerates after menopause.

The pharmaceutical industry helped to define osteopenia, and it also has the pills to treat it. Call me a skeptic, but I’m guessing they had an interest in seeing a lot of women diagnosed with the condition. Some doctors are suggesting that the drugs used to treat osteopenia are being over-marketed to younger post-menopausal women who may still be at relatively low risk for bone fractures. They argue that the benefits of the drugs used to treat osteopenia are exaggerated and the risks generally are downplayed. If you're still young, consult your physician before taking drugs to treat osteopenia. Otherwise you could be trying to treat a problem that you don’t really have yet.

REFERENCE: P. Alonso-Coello, et al. Drugs for pre-osteoporosis – prevention or disease-mongering? British Medical Journal 336:126-129, 2008.

Monday, September 7, 2009

Is She a Woman?

After 18-yr-old South African Caster Semenya turned in the fastest time of the year in a women’s 800-meter event in 2009, track and track and field’s governing body ordered an investigation into her gender. They're demanding “proof” that she’s actually a female, so they’ve assembled a committee tell them. Let's see, now, a geneticist, an endocrinologist, a gynecologist, and a psychologist are getting together to determine the sex of…

It sounds like the beginning of a bad joke, but it’s not. Legitimate physiological and anatomical “gender confusion” can be caused by sex hormone imbalances, tissue unresponsiveness to sex hormones, genes that don’t turn on properly during fetal development, or even sex-determining genes located on the wrong chromosome (in rare cases, an XY male can develop the characteristics of a female).

Sports federations should develop rules that allow gender determination (for the purposes of sports competition) before an athletic event, not afterwards, in the public eye. One can only wonder about the emotional damage about to be done to young Caster Semenya.

Thursday, September 3, 2009

New Strategies Against Superbugs

Antibiotic-resistant bacteria are cropping up everywhere. There hasn’t been a major breakthrough in the development of antibiotics since the 1960s. Are we losing the battle against antibiotic-resistant bacteria?

There aren’t any new weapons in the arsenal just yet, but some scientists remain optimistic. According to a recent article in Scientific American, strategies currently under development include: 1) developing “narrow spectrum” antibiotics that target just one bacterial species at a time, 2) preventing pathogenic bacteria from causing disease in humans without actually killing them, 3) searching among bacterial species for antibiotics that bacteria use against each other in nature, and 4) genetically modifying antibiotic-producing bacteria so that they can be grown easily in culture.

We’ll probably never win against the bacteria, but we can keep trying to stay one step ahead.

REFERENCE: C.T Walsh and M.A. Fishbach. New Ways to Squash Superbugs. Scientific American pp. 44-51, July, 2009.

Thursday, August 27, 2009

Can You Taste Bitter Foods?

About 25% of the human population does not perceive vegetables such as broccoli, cabbage, or Brussels sprouts as bitter-tasting. The rest of us perceive these vegetables as either mildly bitter or obviously bitter. These differences are determined by a gene that has two variations, or alleles – one for “bitter taster” and one for “non-taster”. The bitter taster allele is dominant, so if you have at least one copy of it you will perceive Brussels sprouts as mildly or intensely bitter.

At what point in human evolution did the ability to taste bitter foods first appear? Recent DNA analysis of a bone of a Neanderthal (an extinct line of archaic humans) indicates that they possessed the bitter taster allele. Therefore, the ability to taste bitter foods probably evolved more than half a million years ago, before Neanderthals and modern humans diverged from a common ancestor.

Evolutionary biologists believe that the ability to perceive bitter taste may have discouraged early humans from eating bitter-tasting plants, some of which are toxic if ingested in large quantities.

Thursday, August 20, 2009

Measuring Groundwater Depletion

Scientists are using satellite data to measure changes in the amount of water in underground aquifers. How do they do it? Satellite speed is affected by the pull of gravity, which is partly determined by how much water is underground near Earth's surface. As the first of two satellites approaches a region of the Earth with a large underground aquifer, the pull of gravity increases and the satellite speeds up briefly, increasing the distance between it and a trailing satellite. As the second satellite passes over it too speeds up briefly, closing the gap again. By measuring the changes in distance between the two satellites as they pass over the aquifer and then comparing those distances from year to year, scientists can determine changes in the pull of gravity over time and then estimate how much water has been gained or lost.

Using this technology, scientists have discovered that in just six years, one of the largest aquifers in India has lost a volume of water equal to a lake 30 feet deep and nearly 5,000 square miles in surface area. Most of the groundwater consumed in the region is used for agriculture. Nobody knows how large the aquifer really is or how long it would take to deplete it, but losses of this size just are not sustainable in the long run.

We can expect more of this kind of useful information as the satellite technique becomes more sophisticated. But will we choose to change our water use practices as a result of what we learn?

Saturday, August 15, 2009

Breast-Feeding and Breast Cancer

A recent study in the Archives of Internal Medicine raises the possibility (but does not entirely prove) that breast-feeding may lower the risk of breast cancer among women at high risk for the disease. The study gathered data from over 60,000 women who had reported at least one pregnancy by 1997. Among women with close relatives who developed breast cancer, those who breast-fed for a period of time had only 41% as many breast cancers by 2005 as women who had never breast-fed. The lowered cancer incidence was only seen among women at high risk for breast cancer; women with no family history of breast cancer did not benefit from breast-feeding.

Why doesn’t this study prove once and for all that “breast-feeding prevents cancer”? Because it only shows an association between breast-feeding and lowered cancer risk - cause-and-effect has not been proved. Perhaps women who choose to breast-feed are more health-conscious overall. Perhaps they exercise more or have a better diet, and that’s actually what lowered the cancer risk. Further research will be needed to tease out the details.

Wednesday, August 12, 2009

Is Running Hard on Knees?

Runners are often told (usually by non-runners) that running is hard on their knees. According to commonly held belief, the constant pounding wears out or damages knee cartilage and leads to either knee injury or an increased likelihood of osteoarthritis later in life.

But the available scientific evidence suggests that running is not a risk factor for knee osteoarthritis, and may in fact keep you healthier later in life. In one study, runners were compared to age-matched non-runners over an 18-year period. There was no difference in the rate of development of osteoarthritis between the two groups. In another study, overall disability rates in runners increased at only one quarter of the rate seen in age-matched sedentary persons.

A major risk factor for knee osteoarthritis is not running per se; its having had a previous knee injury. That is why there is so much osteoarthritis among former N.F.L. football players and former soccer players. But if you’re a recreational runner and manage to stay injury-free, don’t worry about wearing out your knees – just keep running!

Thursday, August 6, 2009

The Spleen Stores Monocytes

Shortly after severe tissue damage such as that caused by a heart attack or an infection, the number of monocytes, the white blood cells that eventually mature into macrophages, increases dramatically in the blood. These new monocytes appear too quickly to have been newly produced from stem cells in bone marrow. So where do they come from?

Apparently they come from the spleen. The spleen stores up to ten times as many monocytes as there are in the bloodstream at any one time. When a tissue is injured the spleen releases its stored monocytes, which then migrate to the site of injury, develop into macrophages, and participate in the cleanup and repair process. It’s a pretty efficient use of resources, when you think about it - a virtual army of monocytes is kept on standby, ready to be deployed when needed.

Monday, August 3, 2009

Buying/Selling Kidneys

A Brooklyn businessman named Levy-Izhak Rosenbaum was arrested in New Jersey in 2009 for allegedly trying to broker the purchase of a kidney for $160,000. According to the criminal complaint filed against him, Mr. Rosenbaum told an undercover agent that he could arrange for a live kidney donor from Israel, and that they would then fabricate a fictitious “relationship” between the donor and the recipient so that the hospital in the U.S. would not become suspicious.

The Rosenbaum case is just one example of the shadowy black market in human organs worldwide. The World Health Organization estimates that about 10% of the more than 60,000 kidneys transplanted each year come from living donors who have sold their kidneys strictly for money. The temptation is hard to resist, especially for donors from poor countries where the choice may come down to selling a kidney or selling a child. The practice is not even illegal in some countries (Pakistan is an example), and as a result those countries are rapidly developing thriving “transplant tourism” enterprises.

What, if anything, could be done about the shortage of organs for transplantation?

Saturday, August 1, 2009

What Happened to the Neandertals?

The cover story of the August 2009 issue of Scientific American discusses the latest evidence and hypotheses for why the archaic humans called the Neandertals disappeared from Europe around 28,000 years ago. Older theories, that the Neandertals either interbred with modern humans or died in wars against them (the love versus war hypotheses), seem to be losing favor. A more recent hypothesis is that there were frequent and rapid changes in climate in Europe at the time, and that modern humans, by virtue of being more advanced in certain ways, were better able to adapt to the changes in weather and food supplies. The article goes on to describe the likely cultural, behavioral, and biological differences between the Neandertals and modern humans who lived in Europe 35,000 years ago, and how these differences might have affected modern humans’ success or the Neandertals’ ultimate failure.

Saturday, July 25, 2009

Birth Control Method Failures

In Human Biology (Chapter 16) there’s a table of data adapted from U.S. Food and Drug Administration data, which lists the approximate failure rates of various contraceptive methods. I’ve always felt that the reported failure rate for condoms of 10-20% seemed awfully high. Condoms are supposed to work, right?

Now there’s an explanation. Apparently, for both condoms and withdrawal there’s a big difference between “perfect use” and “typical use”. If a couple actually uses a condom every time (no exceptions, folks), the annual failure rate is only about 2%. For withdrawal every time, the failure rate is about 4%. The problem is that in the heat of passion some couples “forget”, or convince themselves that not using a birth control method just this once won’t be a big deal. Under these more typical use conditions, the failure rates of condoms and of withdrawal are indeed closer to 20% per year.

If you’re going to rely on these contraceptive methods, don’t cheat!

REFERENCE: R.K. Jones. Better than nothing or savvy risk-reduction practice? The importance of withdrawal. Contraception 79:407-410, June, 2009.

Tuesday, July 21, 2009

Percocet, Vicodin May be Banned

A federal panel of experts advised the Food and Drug Administration (FDA) this month to ban two popular prescription painkillers, Percocet and Vicodin, from the market. The panel also recommended that the maximum allowable dose of acetaminophen in over-the-counter pills such as Tylenol be reduced from 500 mg to 325 mg. The FDA is expected to accept the panel’s recommendations.

Percocet and Vicodin are comprised acetaminophen plus a narcotic. According to the panel of experts, there is now sufficient evidence to conclude that high doses of acetaminophen over prolonged periods of time can cause liver damage.

It's worth noting that nearly all drugs, even some very good ones, can have unwanted side effects if they are abused.

You can read or see the news reports on the panel’s findings by Googling “FDA”, “Percocet”, and “acetaminophen”.

Sunday, July 19, 2009

Getting That Caffeine Buzz

The latest entry into the world of marketing hype - “energy shots”, a mere two ounces of bad-tasting liquid loaded with caffeine. Manufacturers won’t say how much caffeine for proprietary reasons (and probably to add to the drinks’ mystique), but most energy shots are thought to contain on the order of 120-200 mg. That’s the equivalent of one to two ordinary cups of coffee or a 16-oz energy drink.

Energy shots may also contain B-vitamins, amino acids and various plant extracts, but these aren’t likely to give you much of an energy boost despite the products’ claims. And then there’s the cost – upwards of $3 apiece.

If it’s a caffeine buzz you need, what’s wrong with plain-old maximum strength (200 mg) No-Doz? It was your grandfather’s drug of choice nearly 50 years ago for pulling an all-nighter, and it still works. Plus it only costs about 20 cents per dose.

Saturday, July 11, 2009

Caloric Restriction and Longevity

It has been known for some time that severe caloric restriction can retard the aging process and prolong the life of a variety of species, from worms to mice. But skeptics of the idea that caloric restriction might also slow the aging process in humans point out that the metabolisms of worms and mice are quite different from that of humans.

Now a new study reports that caloric restriction slows the aging process in primates, too. Macaque monkeys that have been on a calorie-restricted diet (by 30%) for the past 20 years are living longer and are healthier than their age-matched control counterparts. Excluding animals that died of non-age-related causes (accidents for example), 50% of the animals on a normal diet have died of age-related causes, compared to only 20% in the restricted-diet group. The calorie-restricted animals also have fewer age-associated diseases such as diabetes, cancer, and cardiovascular disease. The study is still ongoing.

Wednesday, July 8, 2009

Wildfires, Evolution, and Ecosystems

Fires set by the forces of nature have existed on the Earth since the dawn of time, and as a result some plants have evolved to survive fires rather well. A few plants even require an occasional fire in order to release their seeds. But here’s an interesting notion; did certain plants evolve to encourage the spread of wildfires once they’ve started? After all, if the plant could survive the fire it might be a good way to kill off the competition. For those of you interested in evolutionary processes, see the recent well-referenced opinion article in the New York Times.

Sunday, July 5, 2009

Swine Flu Takes Hold in Argentina

Swine flu just won’t go away. A recent a sharp uptick in the number of deaths from swine flu in Argentina has moved that country into third place for the most swine flu deaths, after Mexico and the United states. And the timing couldn’t be worse; it’s winter in South America, the season when influenza viruses typically spread the easiest. Of special concern is that the death rate in Argentina (1.6%) is more than three times the world average.

We need to keep an eye on this pesky bug. Who knows what it could do in North America NEXT flu season? For the latest information on swine flu (also now called Pandemic H1N1), see the World Health Organization website.

Wednesday, July 1, 2009

Is Being Overweight a Health Risk?

It depends on the question - a health risk for what? People who are overweight, defined by the U.S. government and the World Health Organization as a Body Mass Index (BMI) of between 25 and 30, apparently do have a slightly increased risk for certain diseases such as diabetes, coronary artery disease and hypertension. But for other parameters, such as risk of death, the evidence is not that clear-cut. In fact, a recent study of over 11,000 Canadian adults reveals that as a group, people who are defined as overweight have a slightly lower risk of death than the normal-weight group, though not by much.

Taking this new mortality data into account and reviewing the graph in the essay in Human Biology, one wonders whether the range of “normal” weight shouldn’t be shifted about 3 BMI to the right. A word of caution, however; the shape of the weight-vs.-risk curve is likely to be different for every disease, age group, etc. It’s probably going to be impossible to come up with a perfect functional definition of overweight, no matter how much we’d like to.

Sunday, June 28, 2009

The Pandemic of 2009

The World Health Organization has officially declared a pandemic as a result of the rapid worldwide spread of Influenza A (H1N1), formerly known as swine flu. But that does NOT mean that a lot of people will die. By definition, a pandemic is simply a widespread outbreak of a new human flu virus that spreads rapidly from human to human, causing human illness.

Some flu pandemics cause only mild symptoms and few deaths – others can be quite deadly. The best-known pandemics of the last century were the deadly Spanish flu of 1918 (20-40 million deaths), and the milder Asian flu of 1957 (1-4 million deaths) and Hong Kong flu of 1968 (also 1-4 million deaths). In contrast, the milder seasonal flu that many of us get nearly every year kills “only” about a quarter of a million people each year.

Pandemics are of concern to public health officials (and the public!) because the virus spreads so quickly and because the consequences of the spread cannot always be predicted in advance. Fortunately, it now appears that this pandemic will be no more deadly than the typical seasonal flu that many of us get nearly every year. Most people who become infected with Influenza A (H1N1) are recovering without the need for medical care. But it could have been otherwise, and that’s why health officials were so concerned at first and why they are still watching it closely.

The other flu we worry about is avian flu, also known as bird flu. Avian flu is VERY deadly in the few cases in which it has been caught from birds, but human-to-human transmission is still exceedingly rare.

Wednesday, June 24, 2009

Freeze Your Eggs

Okay, so you’re a woman in her thirties who wants to have children some day but has not yet met “Mr. Right”. What to do? Well, some women have made the decision to freeze some of their eggs before their reproductive clock stops ticking, just in case. The basic techniques are readily available at any fertility clinic; stimulate egg maturation hormonally, harvest some eggs, and then (instead of fertilizing and implanting them) just freeze them.

Worldwide, only about a thousand children have been born from previously frozen eggs. In contrast, over 50,000 babies are born each year in the U.S as a consequence of in vitro fertilization and implantation (Human Biology 5th ed., p. 394). Obviously, the idea of older single women freezing their eggs has not yet caught on. But it just might!

See “Why I Froze My Eggs”, by Rachel Lehmann-Haupt. Newsweek May 11, 2009, pp. 50-52.

Tuesday, June 23, 2009

Steve Jobs' New Liver

It’s not official, but there are reports in the news media that Steve Jobs, CEO of Apple computers, received a liver transplant recently at an undisclosed location in Tennessee (The New York Times, June 23; “A Transplant That is Raising Many Questions”).

Normally, patients who need an organ transplant place themselves on the transplant list of one of eleven regional Organ Procurement Organizations (OPOs) in the U.S. Waiting times can vary. When an organ becomes available the regional OPO offers it to a patient already on its list, with the highest priority given to the sickest patients and those who have been on the list the longest time.

Most patients sign up for the transplant list at only one OPO, because insurance companies will only pay for an organ transplant performed in a person’s “home” OPO. Nevertheless, patients who are willing to pay for the transplant themselves (and with access to a plane so they can get to the hospital within six hours) can increase their odds for a transplant by placing themselves on the transplant lists of several different OPOs simultaneously. No one has said whether or not Mr. Jobs was on more than one list at the time of his transplant, or how long he waited for his new liver.

For a discussion of whether the current organ allocation system is fair, see “How Should We Allocate Scarce Organs?” in Human Biology 5th ed., pp. 368-369.

Thursday, June 18, 2009

Stretching and Sports Injuries

Does stretching before exercise reduce the risk of sports injuries? Many coaches, trainers, and athletes swear that it does, but no one knows for sure because the critical experiment has never been done.

Now researchers are attempting to do the experiment. Sponsored by USA Track & Field (USATF), the researchers are currently enrolling people who run at least 10 miles per week. Participants must agree to be assigned randomly to either the "stretch" or the "no-stretch" group and to adhere to the study protocol for three months. Runners in both groups are expected to report their injuries during the study period.

Runners can apply to be participants at So far several thousand runners have signed up, though not all of them have completed the study protocol and submitted their reports. The results will be made public as soon as enough runners have completed the protocol for there to be a statistically significant difference between the groups, or when enough data has accumulated to show that there is no difference. Ultimately, up to 10,000 runners may be needed.

Runners, this is your golden opportunity to contribute to the advancement of science.

Monday, June 1, 2009

Dwindling Phosphorus Supplies

The world’s supply of phosphorus for agricultural fertilizers is dwindling, according to a recent article in Scientific American. Global reserves are expected to run out in about 100 years unless new reserves are found or better techniques are developed for extracting phosphate from phosphate-rich rock.

As phosphorus supplies decline and as the world demand for agricultural fertilizers grows, we can expect fertilizer price spikes, phosphate shortages, and perhaps even disruption of food production. Countries with large phosphorus reserves such as Morocco will benefit economically. Morocco could be among the wealthiest nations in the world in 50-100 years.

Tuesday, May 26, 2009

Cleansing Blood With Magnets

Researchers at Harvard University are working on an innovative method for treating blood infections - drawing the bacteria out of blood with magnets. They mix infected blood with tiny antibody-coated magnetic spheres only 1/8 the size of red blood cells. The antibodies on the spheres attach to bacteria in the blood, and then the spheres and the bacteria are drawn off together using a powerful magnetic field.

In initial experiments the method removed up to 80% of the bacteria in small samples (10-20 ml) of blood. However, several questions remain to be unanswered: 1) Can the method be tooled up to cleanse the larger volume of blood in human patients? 2) Will reducing the bacterial or fungal load in a patient’s blood actually improve the patient’s recovery? 3) What might happen to the patient if a few magnetic beads are not removed from the blood before it is returned to the patient?

It may be awhile before we know if the method can be used safely and effectively to treat blood infections in human patients.

Saturday, May 16, 2009

What to Call Swine Flu

What should be the proper name for swine flu, now that we know that people are catching it from infected people, and not from swine? The World Health Organization has stopped calling it swine flu in favor of “influenza A (H1N1)”. But that name also applies to one of three strains of seasonal flu and to the deadly 1918-1919 Spanish flu (which didn’t even originate in Spain!) The U.S. Centers for Disease Control (CDC) calls it both “novel influenza A (H1N1)” and “H1N1 flu (swine flu)” on its website. Of course the Mexican government objects to calling it “Mexican flu”.

An article on what to call this virus appears this week in Science.

Thursday, May 14, 2009

Food Shortages and World Stability

Will the world ever simply run out of food? A recent article in Scientific American suggests that it won’t be that simple. The article’s author postulates that local or regional food shortages will be followed by starvation, which in turn could result in the collapse of governments and a rise in terrorism in poor countries and refugee problems in neighboring countries. Countries most likely to become the first failed states include Somalia, Sudan, Zimbabwe, and Chad, according to several international peace groups. Destabilization of governments could eventually spread worldwide, if food prices rose beyond the means of less wealthy nations.

Could such a scenario be prevented? The article goes on to say that in the long run, maintaining the world’s food supply will require drastic action, including solving the global warming problem, conserving fresh water, and stopping the current rate of topsoil losses. Otherwise, we may all be fighting each other for the last scraps of food sooner (perhaps in just hundreds or thousands of years) than we think. It’s something to think about.

Reference: “Could Food Shortages Bring Down Civilization?” Scientific American pp. 50-57, May, 2009.

Friday, May 8, 2009

Swine flu

It first appeared in Mexico in March. Popularly called swine flu, the H1N1 virus turns out to have a strange mixture of viral genes; 48% of its genes are from swine flu viruses, 34% are from avian flu viruses, and 17% are from human flu viruses. A key feature of the H1N1 virus is that it can be transmitted from human to human. By yesterday, swine flu had infected nearly 2,400 people, mostly in Mexico and the United States, killing 44. Where it came from, how far it will spread, and whether it will cause a pandemic remain unanswered questions. The World Health Organization’s influenza pandemic alert is currently at phase 5, just below a phase 6 full-alert.

There have been plenty of reports in the popular press about swine flu, some true, some not. For example, initial reports of a very high death rate from swine flu had to be revised downward once it was determined that many of the deaths attributed to swine flu were not caused by H1N1. Still, a death rate of nearly 2 % in healthy adults is quite high for any flu virus. Two percent of the world’s population is how many million people???

For authoritative updates about swine flu, try the news section of a magazine such as Science (see this week’s report) or the website of the World Health Organization.

Friday, May 1, 2009

Homo floresiensis made tools

Homo floresiensis, the species of extinct “little people” discovered recently on the island of Flores in Indonesia (see Human Biology 5th ed., pp. 520-521) apparently made and used stone tools, according to a recent report in Science. What makes this feat so impressive is that H. floresiensis has a very small brain by hominid standards. The discovery of H. floresiensis is causing anthropologists to re-think their long-standing hypothesis that the intelligence needed for making tools came only after, and as a consequence of, a large brain.

Modern humans who inhabited the area thousands of years later also made the same kinds of stone tools. Did modern humans interact with and learn from H. floresiensis, or did they develop the same tool-making techniques independently? No one knows for sure yet.

Monday, April 27, 2009

Correlation Versus Causation

According to a study of the nearly 140,000 women who were enrolled in the Women’s Health Initiative, women who breast-fed their babies had a lower risk of developing heart disease and diabetes later in life than women who did not breast-feed their babies. The headline of the New York Times article about the research read “Breast-Feeding Benefits Mothers, Study Finds”. Is this a correct summary of the research?

The answer is “NO”! This is a classic case of the common misunderstanding about the relationship between correlation and causation. Yes, there is a clear correlation between breast-feeding and a lower risk of diabetes and heart disease later in life, according to the study. But that is not proof that the act of breast-feeding is what reduces the risk. What if women who breast-fed their children are just more health conscious overall throughout life? What if they exercise more often, or have healthier diets?

A more correct headline would be “Breast-Feeding May Benefit Mothers, Study Suggests”. Indeed, the article itself goes on to say that some experts are cautioning that an association (between breast-feeding and health benefits) does not prove a causal relationship, and that more research would be needed to determine the exact cause of the effect (lower risk).

Friday, April 24, 2009

Access to the "Morning-After" Pill

The F.D.A. is lowering the age limit for obtaining Plan B, the “morning-after” contraceptive pill. Soon anyone over the age of 17 will be able to purchase Plan B over the counter at pharmacies and health clinics, simply by providing proof of age.

News articles on the upcoming change appeared in most major papers yesterday, including the Los Angeles Times.

Sunday, April 19, 2009

Boosting Cardiac Repair Mechanisms

Conventional wisdom holds that a damaged heart cannot repair itself after a heart attack because the heart does not have the ability to produce new cardiac muscle cells throughout life. But now scientists have demonstrated that cardiac muscle cells are being replaced throughout life, though at a very slow rate - only about 1% of the heart muscle cells are replaced each year in young adults. The rate falls gradually to about half a percent per year by age 75. Over a lifetime, though, about 45% of the cardiac muscle cells present at birth will have been replaced.

One percent per year is not fast enough for the heart to repair itself under natural conditions after a heart attack. But the fact that it occurs at all is giving researchers new hope. If future research were to improve our understanding of how cardiac muscle cell replacement is regulated, perhaps new drugs or treatments could be developed that would jump-start the process after a heart attack.

It could be decades before any patients are actually helped by the new findings, but that’s the way science goes…..a little breakthrough here, a little breakthrough there, and pretty soon there’s real progress!

Thursday, April 16, 2009

Global Warming Tipping Points?

One of the hottest controversies among global-warming watchers these days is whether or not global warming will ever pass a “tipping point”, setting off rapid, unstoppable, and catastrophic climate change. Do climate tipping points even exist? Or will climate change just continue slowly and inexorably for hundreds or perhaps even thousands of years?

No one knows for sure. But well-meaning climate scientists who believe in tipping points warn of doomsday scenarios in an effort to get people to do something about global warming before it is too late. You’ve heard it all before - the Amazon rainforest will become grasslands; the polar ice caps will melt; the seas will rise several meters, flooding most of Earth’s populated areas; ecosystems will be disrupted. Some climate scientists worry that talk of tipping points could backfire. If a tipping point doesn’t happen within the next couple of decades, will people quit worrying about global warming altogether and decide it’s not worth doing anything about? Yawn! I’m bored with this whole subject…….

The best climate models can’t tell us yet whether or not there are tipping points. And therein lies the danger - there may actually be tipping points. Perhaps more likely is that lots of little tipping points in Earth’s complex climate system will add up to acceleration of global warming the higher the temperatures get.

For a recent news article on the subject, see “Among Climate Scientists, a Dispute Over ‘Tipping Points’”, The New York Times, Mar. 29, 2009.

Friday, April 10, 2009

A DNA test for Cervical Cancer

It was bound to happen eventually. The annual Pap smear, the gold standard for over 40 years for detecting cervical cancer, may soon be replaced by a modern, much more specific DNA test for the human papillomavirus that is responsible for most cervical cancers. The cost of the test is currently around $20-30, but the test is so accurate and specific that women may only need the test once every 5-10 years.

A comparative study of the effectiveness of the new DNA test (HPV test) versus the Pap smear (cytologic test) in preventing cervical cancer deaths was conducted in India with funds provided by the Bill and Belinda Gates Foundation. After just eight years, the study showed that the DNA test reduced cervical cancer deaths by nearly 50% compared to the Pap test. Significantly, not one woman whose DNA test for HPV was negative died of cervical cancer during the study period.

Saturday, April 4, 2009

Birth Dating Human Cells

How can scientists determine the age of human cells? How frequently are human cells replaced, if at all?

In 2005 scientists hit upon an ingenious method that takes advantage of a dark period in recent world history - the above-ground testing of nuclear weapons between the mid-1950s and 1963. Nuclear weapons testing resulted in a sharp spike in carbon-14 levels worldwide. The levels peaked in 1967 and have since declined as carbon-14 diffused and equilibrated with the atmosphere, the oceans, and the biosphere. Carbon is incorporated into the chemical components of all new cells, of course, including DNA. It turns out that the carbon-14 levels in nuclear DNA correspond very closely to the atmospheric levels at the time the DNA was synthesized. So by comparing the cells’ nuclear DNA carbon-14 levels to a chart of atmospheric cabon-14 levels each year, one can determine the cells’ birth date.

How does this help us determine cell turnover? Think about it: if all of the cells in a piece of tissue are the same age as the individual, then cells are not being replaced throughout life. But if the average cell age is much younger than the individual, then cell turnover must be relatively high. The scientists who developed the cell-dating technique report that neurons in the cerebral cortex (the most highly developed area of the brain) do not undergo significant replacement throughout life - you’re born with all the cortical brainpower you’re ever going to have. In contrast, cells lining the intestine are replaced frequently.

Wednesday, April 1, 2009

Earth's Dwindling Arctic Sea Ice

A news article in Science last week (Science Mar. 27, p. 1655) suggests that polar ice may disappear entirely from the Arctic Ocean during the summer in less than 30 years. According to the article, scientists narrowed 23 different climate models down to the six that best fit the data for the ups and downs of sea ice from winter to summer in the past. They then used the models to predict when the summer ice would disappear completely from the Arctic Ocean. The best estimate is somewhere around 2037.

You may live to see polar bears become nearly extinct in the wild. On the bright side (if there is one), marine shipping could occur between the Atlantic and Pacific Oceans through the Arctic Ocean during the summer months.

Thursday, March 26, 2009

The PSA Test for Prostate Cancer

For over 20 years some health professionals have been recommending that men over 50, and men as young as 45 if they belong to a high-risk group, be screened for prostate cancer by means of a PSA test (see Human Biology 5th ed., table 18.4). The PSA test measures the level of prostate-specific antigen, a protein from prostate cells. An elevated serum PSA indicates that prostate cancer might be present, in which case the next step is a biopsy to determine for sure.

When the PSA test was first introduced in 1987, scientists thought it might lead to as much as a 50% reduction in prostate cancer deaths. But now it seems that it may not save lives after all. In a study of 77,000 U.S. men, the 10-year death rate from prostate cancer was the same in a group who had an annual PSA test for six years plus a digital rectal examination for four years, compared to a control group who were never tested over the same time period. The study may need to be continued out for another decade or so to determine whether the PSA test has any usefulness over the longer term, however.

How can a test that accurately detects prostate tumors not save lives? Apparently the answer is that most prostate cancers are so slow-growing that older men are likely to die of something else first, even if they do have a diagnosis of prostate cancer. For older men, skipping the PSA test altogether may someday be safe option.

By the way, a digital rectal examination is not some sort of digital readout. It's a physician’s gloved digit, or finger.

Friday, March 20, 2009

If Not Bird Flu, Then.....What?

In Human Biology: Concepts and Current Issues we discuss the possibility that a human pandemic might be caused by the bird flu virus, H5N1, if the virus evolves to become easily transmissible between humans. But so far it hasn’t happened. Where will the next great human pandemic come from, if not from the bird flu virus? No one knows for sure, but the smart money is on pathogens living in animal species closely related to humans, such as non-human primates. In fact, that’s precisely how HIV developed – an evolving virus in monkeys jumped to chimpanzees and then to humans.

Knowing this, how might we prevent the next pandemic, or at least have some warning that it was coming? One intriguing possibility would be to keep a close eye on diseases that develop in humans who are in close contact with wild animals. To learn more, read “Preventing the Next Pandemic”, by Nathan Wolfe (Scientific American, April, 2009, pp. 76-81), and then check out the website of the Global Viral Forecasting Initiative. In fact you can download a .pdf file of the Scientific American article directly from the the GVFI website.

Sunday, March 15, 2009

Obama Lifts Stem Cell Ban

Last week President Obama signed an executive order lifting the restrictions on stem cell research laid down by President Bush in 2001 (See the Current Issue in Human Biology 5th. ed., pp. 72-73). Most political analysts expect Congress to enact new legislation soon that will permit federal research dollars to again begin to flow for promising stem cell research projects.

President Obama’s executive order will permit federally funded researchers to use the hundreds of stem cell lines in existence today, as well as new stem cell lines created by private funding in the future. But there is still a prohibition in place, called the Dickey-Wicker Amendment of 1996, which prohibits federal funding for research “in which human embryos are created, destroyed, discarded, or knowingly subjected to risk of injury or death”. So while federally funded researchers will be able to use stem cell lines created by private funds (because they themselves did not destroy any embryos), they will still be prohibited from creating their own new cell lines from human embryos.

How long can the Dickey-Wicker Amendment can stand up in this new climate of stem cell research permissiveness? It's anybody’s guess. The debate continues…

Wednesday, March 11, 2009

A Way to Cure HIV Infection?

Modern HIV treatment drugs suppress an active HIV infection well enough that an HIV-infected person can live a relatively normal life. But they don’t cure an HIV infection because some viruses lie dormant inside living cells, out of reach of suppressive drug therapy. For that reason, high-cost suppressive therapy needs to be continued throughout the life of the patient, just so the drug is present whenever viruses do come out of hiding. What is needed is a way to get rid of the latent viruses lying dormant inside cells, once and for all.

A new approach is anti-latent therapy – therapy designed to prevent dormant viruses from staying dormant and hidden. The idea is to force any remaining dormant viruses to become active again so that they can be targeted and killed by suppressive therapy. A combination of anti-latent therapy and suppressive therapy just might wipe out an HIV infection completely. At least, that’s the idea.

Wednesday, March 4, 2009

Designer Babies? - Not Yet!

On Tuesday, a fertility doctor with clinics in New York and Los Angeles said that within six months he would offer couples the chance to choose some of their baby’s physical traits. Dr. Jeff Steinberg said that his company, Fertility Institutes, would use in vitro fertilization (IVF) techniques combined with pre-implantation genetic diagnosis (PGD) to help couples select from among their IVF embryos for the one with the best chance of having their preferred hair and eye color and even skin tone. Fertility experts scoffed that it could be done with any reliability. And when right-to-life advocates objected strenuously and his clinic received hundreds of calls, Dr. Steinberg backed down – at least for now. According to an article in the Daily News later the same day, he said he’ll stick to helping couples concerned about known genetic disorders.

The unresolved issue of whether would-be parents should be allowed to create designer babies is a train wreck waiting to happen. New York, for example, does not have laws against using PGD strictly for cosmetic purposes, so clinics such as Dr. Steinberg’s are free to promise what they will. Nevertheless, it’s a slippery ethical slope they’re on. The issue is discussed in Human Biology 5th ed., pp. 396-397.

Sunday, March 1, 2009

Walking Like a Modern Human

Well-documented fossilized 3.8 million-year-old footprints show that our early ancestors walked with a decidedly ape-like primitive gait, with bent knees, short steps, and a predominant point of impact on the heels. It may have taken several million more years of evolution before changes in our ancestors’ physical structure allowed them to walk with the long stride of modern humans. Recent analysis of 1.5 million-year-old footprints in Kenya indicates that the footprint-makers (most likely Homo erectus) had a long stride and the ability to push off with the big toe, as we do. The footprints also show that by 1.5 million years ago, foot anatomy was very much like ours.

Friday, February 27, 2009

The Dark Side of Gender Preference

In China, 120 boys are born for every 100 girls. Experts think that the recent trend (since 1980) is the result of China’s “one-child” population-control policy, combined with a traditional society in which the eldest boy inherits the family land and is responsible for taking care of aging parents. So if a couple is planning on having just one child, usually they will decide it should be a boy. The boy/girl sex ratio is highest in rural areas; in cities, the earning power of women tends to be accompanied by a more normal sex ratio.

What can be done about it? One approach is educational programs to encourage couples to value daughters equally with sons; another is to allow families whose first child is a girl to have a second child; still another is to encourage young couples to live with her parents rather than his. The government is even offering cash payments for girls in some regions.

Wednesday, February 18, 2009

PRP Therapy for Connective Tissue Injuries

If you’ve ever injured a tendon or ligament you know how painful such injuries can be. You also know that injured connective tissue takes longer to heal than injured muscle tissue. That’s because there is generally very little blood flow to connective tissue, especially in areas in and around fluid-filled joints. As a result, very few blood platelets and white blood cells are delivered to the area to help with tissue repair.

Experts in sports medicine now think they have a potential solution. It’s called “platelet-rich plasma therapy”, or PRP for short. The method is surprisingly straightforward. A sample of the patient’s own blood is enriched in platelets by removal of the blood cells and most of the water and electrolytes. The remaining platelet-enriched plasma is then injected directly into the injured joint or connective tissue. The theory is that the platelets will release proteins involved in tissue repair and attract other tissue-repair cells to the area, speeding the healing process.

Does PRP therapy work for such common connective tissue injuries as rotator cuff strains, Achilles tendon injuries, and tennis elbow? Clinical trials are underway in several countries, including the U.S., to find out. Meanwhile, some professional athletes have already tried it, including Los Angeles Dodgers’ baseball pitcher Takashi Saito and Pittsburgh Steelers’ receiver Hines Ward. Ward has his answer already; he was able to play in the Superbowl just two weeks after a knee injury that generally sidelines players for 4-6 weeks.

Friday, February 13, 2009

Using Urine to Diagnose Disease

Your body gets rid of over a thousand different small metabolic waste molecules, called metabolites, by excreting them in the urine. In certain diseases one or more of these metabolites may be elevated in urine. Scientists now believe that through “metabolomics” – the study of metabolites – it may be possible to diagnose certain diseases even before symptoms appear in the patient.

The concept is simple; once you know the normal range of excretion of metabolites in urine, a change in the excretion of one or more metabolites might signal the presence of a specific disease. For example, scientists at the University of Michigan measured 1,126 metabolites in urine and found that one of them in particular, called sarcosine, showed promise as a marker for metastatic prostate cancer. The findings were reported in Nature this month.

Unlike blood, urine is easily collected in large quantities by non-invasive techniques. (Put more bluntly, you just pee into a cup!) As the field of metabolomics comes of age, perhaps some day it will be possible to screen for dozens of diseases at once.

Monday, February 9, 2009

FDA Approves a Genetically Engineered Drug

The first human drug produced by livestock genetically engineered to contain a human gene has now been approved by the Food and Drug Administration. A company called GTC Biotherapeutics developed a herd of goats (Figure 20.10 of Human Biology) that contain the human gene for antithrombin III, a protein used to prevent blood clots in people with hereditary antithrombin deficiency. One advantage of using farm animals is that larger quantities of human proteins can be obtained from the milk of genetically engineered animals than from human blood. One of GTC’s goats, for example, can produce as much antithrombin/year as the amount that can be extracted from 10,000 gallons of human blood!

How did GTC manage to get the antithrombin to be produced in milk, so they could harvest the protein by milking the goats instead of bleeding them? Simple concept, really - they linked the human gene for antithrombin to a goat gene for a milk protein.

Thursday, February 5, 2009

8 Babies - How Did It Happen?

Last week a 33-year-old unwed California women gave birth to octuplets. Experts say that there are only two plausible explanations; they could have been conceived naturally if the woman had taken heavy-duty fertility drugs and had ovulated eight eggs at once, or an IVF clinic deliberately implanted eight embryos, against all current IVF treatment guidelines.

The woman’s mother has said that the woman had frozen embryos left over from previous IVF cycles, and that she had embryos implanted last year. But who would implant eight embryos?! It’s no surprise that the woman’s doctor has not yet come forward to take “credit” for this feat. Ethicists and fertility specialists are in agreement that implanting eight embryos during one IVF cycle would be unethical and irresponsible. Doctors apparently offered the woman the opportunity to reduce the number of embryos early in the pregnancy, but she refused.

This one is likely to be debated for awhile by ethicists and fertility experts. It might even be discussed on Oprah's show some day soon, if the woman can get enough money to appear! Reports are that she is holding out for several million dollars. Good luck.

Note added April 20, 2009: Apparently six embryos were implanted, but two split into twins. The maximum number of embryos which should be implanted is two, according to voluntary guidelines established by the American Society for Reproductive Medicine.

Sunday, February 1, 2009

Scientific Uncertainty and Shared Responsibility

Here’s an interesting dilemma for you: An industrial chemical is known to cause a particular type of cancer in rats. A lifelong employee at the plant that makes the chemical is diagnosed with the cancer, so he sues the company for millions of dollars. Ultimately the employee loses the case and receives nothing, because the company’s lawyers argue (correctly) that the worker could have gotten the cancer from some other source, or that the worker had a genetic predisposition to cancer. In other words, the worker cannot prove scientifically beyond a reasonable doubt that his cancer was caused by exposure to the chemical while working in the company’s plant. Having won the case, the company continues to expose its current workers to the chemical.

Do we consider this to be fair, equitable, and just? Should the entire burden of uncertain science be borne by just one side?

Some lawyers are now arguing for the concept of “shared responsibility” when the scientific evidence leaves room for uncertainty. Perhaps the company should be asked to pay at least a small amount to its workers who develop the cancer as acknowledgment that their chemical might have caused the workers' cancers - not enough for the workers to have “won the lottery” or to bankrupt the company, but at least enough to help defray the workers’ medical expenses. Over time that might cause the company to reconsider continuing to expose its current workers.

What do you think?

Friday, January 23, 2009

Gender Bias in Kidney Transplants

According to a report that will be published shortly in the Journal of the American Society of Nephrology, women over the age of 45 who need a kidney transplant are less likely to get one than men of the same age. This despite the fact that they are no less sick than the men and would benefit just as much as the men by having a kidney transplant.

So why the bias against older women? The researchers aren’t sure, but they speculate that women may be seen as more frail than they actually are by whoever makes the decision to put (or not to put) a female patient on the deceased-donor waiting list or to help them find a live donor. Or, perhaps the women themselves think they are less likely to survive the surgery or benefit from the transplant.

In fact, the researchers found no difference in the survival benefits between men and women, and even between older men and older women. We may need to look carefully at why older women are not getting the transplants they need.

Thursday, January 22, 2009

Antibiotic-Resistant Bacteria

Researchers have recently uncovered more evidence of an increased trend toward antibiotic resistance by Staphylococcus aureus infections, this time in infections in children. As you may know, staph is a nasty little bacterium that can lead to severe skin lesions. According to the report, the percentage of staph infections that were resistant to methycillin, the antibiotic most commonly used against staph, rose from 11.8% in 2001 to 28.1% in 2006.

Health workers worry that someday our current antibiotics just won’t be very effective any more. For more on this topic, see (See “The Growing Threat of Antibiotic-Resistant Bacteria” in Human Biology 5th ed., p. 18).

REFERENCE: Naseri, I., et. al. Nationwide Trends in Pediatric Staphylococcus aureus Head and Neck Infections. Archives of Otolaryngology - Head and Neck Surgery 135:14-16, 2009.

Sunday, January 18, 2009

Young Adults Turn to Sleeping Pills

Prescriptions for sleep medications increased nearly 50% in adults under the age of 45 between 1998 and 2006, according to a report in The New York Times. Among young adults aged 18-24, the use of heavily-advertised prescription sleep medications such as Ambien CR and Lunesta nearly tripled. These drugs truly are safer than older, benzodiazepine-based products, so there would seem to be little reason not to use them to get a good night's sleep.

However, in some cases these drugs may be prescribed too readily. Many of these prescriptions are written when the patient is being seen for something other than a sleep disorder, such as a general medical examination or a menstrual disorder. The worry is not the safety of the drugs per se, but that patients may not be receiving much-needed medical workups to eliminate potential underlying psychiatric disorders before prescriptions are written.

If all you want is a good night's sleep, what about adjusting your behavior or environment a little? You might just get a good night's rest if you were to move out of that noisy dorm and stop drinking 6 cups of coffee a day! Just a thought.

Saturday, January 17, 2009

An Impact of Humans on Evolution

Evolutionary processes may be impacted by human activities, such as trophy hunting for big-game animals. Some of the evidence comes from a study of bighorn sheep published about 10 years ago. The article documents a substantial decline in body size, horn size, and reproductive success among four-year-old (young breeding age) male bighorn sheep in one location in Alberta, Canada over 30 years as the result of the hunting practices that targeted primarily the prime breeding-age males.

Is there a solution to this problem that would still allow trophy hunting? Well, yes there is, and it lies in a key concept of evolution - that the death of an individual animal after his/her reproductive years cannot affect heritable processes. Therefore, hunters should be allowed to harvest only the truly old males; males so old that they are unlikely to be competing successfully with younger, more fit males for females. In bighorn sheep this age is probably about 8 years, when the horns generally form a complete curl. Wildlife management experts are taking heed. Over the years the legal minimum horn length for bighorn sheep has risen in most wildlife management areas from 3/4 curl, to 4/5 curl, and now to full curl. The number of male bighorn sheep harvested each year dropped for awhile, but that’s the price that has to be paid. Sound wildlife management practices based on good science will benefit us all, whether or not you hunt.

Incidentally, a more widespread problem may be commercial fishing. When minimum size limits are set, the surviving female fish are smaller, reproduce at a younger age, and produce fewer eggs. In other words, when humans harvest the big fish, the puny fish are more likely to survive to pass on their genes.

Thursday, January 8, 2009

Focus on Evolution

The January, 2009 issue of Scientific American is focused almost entirely on the subject of evolution. There are articles about Darwin, testing Darwin’s concept of natural selection, the molecular basis of species variation, human evolution, and how creationists misrepresent evolution in an effort to have religious ideas taught in school. In short, it’s a good source for additional reading material for your class on virtually any topic on evolution you might wish to emphasize.

Monday, January 5, 2009

Storing Umbilical Cord Blood

An article entitled “When Medicine Meets Marketing" (Newsweek Dec. 22, 2008, pp. 49-51) would be a good supplementary reading for when you cover the topic of blood in your human biology college course. The article describes how private blood storage companies are waging a fierce marketing campaign designed to convince young parents to bank their baby’s cord blood (for a hefty fee), just in case the stem cells in cord blood might be useful in the future. The scientific background for understanding the article is covered in Human Biology.

Based on what you have learned from the textbook and/or from the Newsweek article, are you more likely to; a) bank your baby's cord blood privately, b) donate your baby's cord blood to a public cord blood bank registry, or c) do neither? On what do you base your choice?