Wednesday, September 28, 2016

Cooler Fabrics

Staying warm indoors is easy; just put on a sweater, sweatshirt, or light jacket. But staying cool under warm conditions indoors has its limits. It's generally not socially acceptable to take off all clothing or even strip down to just a cotton t-shirt in a hot office. But soon there may be a solution. By taking advantage of knowledge of how the human body cools itself, researchers at Stanford University believe that they have developed a clothing fabric that can keep the wearer significantly cooler than other fabrics such as cotton. Their findings are documented in the Sept. 2 issue of Science and explained in layperson's terms in Forbes Magazine.

Except when a person is sweating, the body loses most of its heat as radiant heat energy in the infrared part of the wavelength spectrum. (You can't see infrared radiation because its wavelength is longer than visible light.) The problem is that fabrics such as cotton reflect most of this radiant heat back toward the body; that's partly how they keep the body warm. Understanding this, the researchers started with sheets of opaque polyethylene that allow 90% of IR radiation to pass through (cotton only transmits 5%.) Then they punctured it with tiny needles to allow air to pass through and added a substance that allows the fabric to wick moisture away. Finally, to make the material feel more like traditional fabrics they bonded two sheets of the material to a middle layer of widely spaced cotton mesh.

Then they tested the new fabric. In a room kept at 23.5oC the temperature of bare skin was 33.5oC, skin covered with cotton was 37oC, and skin covered with the new fabric was 35oC. That's fully 2oC lower than cotton, giving the new fabric an advantage in a warm room.

There's no guarantee that the new fabric will catch on with clothing designers. But at least it introduces a new way of thinking about how to create new fabrics for specific purposes, based on human physiology.

Thursday, September 22, 2016

Wearable Activity Monitors and Weight Loss

It may be fun to record how many steps you took today. But does wearing an activity monitor help a person to lose weight?

To find out, researchers at The University of Pittsburgh enlisted nearly 500 people in a randomized trial. For six months, all participants were asked to adhere to a low-calorie diet and to exercise in prescribed ways. After six months the diet and exercise recommendations were continued for another year and a half, but now half of the participants wore an activity monitor and the other half (the control group) did not.

The researchers had hypothesized that those wearing the activity monitors would lose more weight than those in the control group. Surprisingly, that was not the case. In fact, the activity monitor-wearers lost slightly less weight; only 7.7 lb versus 13.0 lb. in the control group.

So what are we to make of this? Not much, except that human beings and their behaviors are, well, complicated. Perhaps wearing an activity monitor reduces diet compliance (self-reported in this study). Or perhaps an activity monitor gives the wearer an inflated perception of how hard they actually are exercising, so that they aren't expending as many calories as they think (physical activity, too, was self-reported). Who knows? For now, all we know is that wearing an activity monitor doesn't help one lose weight.

Tuesday, September 20, 2016

Purposefully Causing the Extinction of a Species

Question: If it were technically possible, should we deliberately cause the extinction of species that we perceive as harmful (to us)? If we could actually eliminate forever the species of mosquitoes that carry certain human diseases such as yellow fever, malaria, and the Zika virus, should we do it?

Think hard on this question, because one day it may be possible. Right now, we know how to modify mosquitoes so that the males are sterile; when these sterile males are released into the wild there is a sharp drop in the mosquito population in the local region, but not a complete extinction because there are still plenty of wild normal males to ensure the survival of the species. But what if you could modify mosquito genes so that they could only produce male offspring? Such a change would wipe out the entire species in short order.

The ides of deliberately causing the extinction of certain species may be morally repugnant to some. But even if its not, we need to be aware of that there may be risks. Time and time again we've seen how the introduction of an invasive species disrupts an ecosystem. What might be the unintended consequence of the opposite scenario; eliminating a species from its ecosystem? If we were to eliminate a species in the wild, it might be wise to keep colonies of the species in captivity so that they could be re-introduced if necessary.

On the political front, who would be responsible for giving consent for a species extinction? Mosquitoes know no political boundaries. Any plan to eliminate a species, even one so universally unloved as a mosquito, should require nearly universal international approval. Don't count on that any time soon.

Wednesday, September 14, 2016

The Presidential Candidates' Plans to Reduce Drug Prices

What are Hillary Clinton's and Donald Trump's views on the skyrocketing costs of prescription drugs in the U.S.? Who, exactly, is to blame for the rising costs, and what could be done about it? There's an article in The Lancet (a British medical journal) last month on the subject. Some of Donald Trump's ideas are not well fleshed out, as is usual for Donald Trump: you just have to trust him. Hillary Clinton, also true to form, focuses her attention on specific changes that she has in mind.

After reading the article I was left with a lot of unanswered questions. For example, why is it that although the U.S. develops most of the drugs, we end up paying more for them than people in other countries? Should drug companies really get tax deductions for their marketing expenses? Why isn't Medicare allowed to negotiate drug prices directly with pharmaceutical companies, as insurance companies and pharmacy benefit management companies do?

There has been a lot of news coverage lately about Mylan Pharmaceuticals' epinephrine injection device called the EpiPen, which contains about a dollar's worth of epinephrine but sells for about $300. It's time to ask whether this is really reasonable.

Thursday, September 1, 2016

New Guidelines for Human/Animal Stem Cell Research

The National Institutes of Health (NIH) is considering updating its guidelines for stem cell research. The proposed new guidelines would allow human pluripotent stem cells to be inserted into non-human vertebrate embryos under certain conditions. Federal funding for such research has been prohibited since 2009 to give NIH time to study the issues carefully.

It seems clear that the NIH wishes to avoid the accidental (or on-purpose) production of human/animal chimeras; animals that are too close to human in their physical, mental, or emotional traits. To avoid this possibility, NIH plans to review carefully any experiments in which the human cells are introduced before the gastrula stage in the embryo - when the three germ cell layers begin to develop. A special restriction is that human cells may not be introduced into primates before the blastocyst stage. Proposals will be reviewed by a special steering committee comprised of scientists, ethicists, and even animal welfare specialists. The committee may consider such things as where the human cells are likely to end up in the animal, as well as how the human cells might affect the animal's physical and behavioral traits.

Why do this type of research at all? Scientists argue that the chimeras produced in this way (perhaps rodents with some human cells or tissue types) would be useful for understanding some human diseases, as well as for drug testing on animal models. Perhaps one day it might be possible to produce human organs suitable for transplant in animals. But that day is a long way off.

What do you think? You have until Sept. 6 to submit your comments NIH.

Caster Semenya Wins Gold at the Olympics

It has been a long and sometimes humiliating road for Caster Semenya, who won the women's 800-meter race at the 2016 Olympics. That's because Caster is thought to have an intersex condition characterized by ambiguous genitalia and quite possibly high testosterone levels - in other words, she may be a "tweener" in terms of gender. After she won the women's 800 meters race at the 2009 World Games, Caster was subjected to humiliating gender determination - by a committee, no less. Cleared to compete again in 2010, she won a silver medal in the 800 meters race at the 2012 Olympic Games (see this blog Aug. 16, 2012).

In an effort to establish a policy for female athletes that could be applied before competition, not after, in 2011 the International Association of Athletics Federations (IAAF) developed a policy based on testosterone levels. The first test case was a woman named Dutee Chand who was prevented from competing as a woman in 2014 because she had testosterone levels above the limit for females. Ms. Chand appealed the decision to the Court of Arbitration in Sport (CAS), based in Switzerland. In 2015 the CAS ruled in favor of Ms. Chand and suspended the IAAF's policy for two years. The CAS argued that there was insufficient evidence to conclude that women with high testosterone levels benefit from such a performance advantage that they should be excluded from competing as females. The court gave the IAAF two years to provide more persuasive evidence for its policy, if it could.

And that's where we stand today. Based on the CAS ruling, there was no way that a defensible policy defining femaleness for the purpose of athletic competition could have been developed for the 2016 Olympics, and so Caster Semenya was quietly allowed to compete again. In a brief statement, the International Olympic Committee said only that it encourages the IAAF to go back to the CAS "with arguments and evidence to support the reinstatement of it hyperandrogenism rules."

For the record, Caster Semenya has always identified herself as a woman. She wasn't looking for the controversy she caused in 2009, and she wasn't looking for it in 2016. She just wanted to compete. And that, after all, is the spirit of the Olympics.