In the past two years, more than 20 children in California have developed polio-like symptoms with paralysis of one or more limbs, according to a press release by the American Academy of Neurology. But the symptoms are not caused by the poliovirus, according to the neurologists who examined five of the patients. There are no signs that the children will ever recover from their paralysis. The most likely hypothesis is that if there is a common cause for these cases of paralysis, it is probably a new virus.
Before we all panic, we should note that these newly identified cases of childhood paralysis are still extremely rare. And so far there is no evidence that the disease has ever been transmitted from one patient to another.
The fact that 20 cases of partial paralysis in California were linked together and identified as a potential new disease is a tribute to the vigilance and power of our current disease surveillance system. The California Department of Public Health is working to identify other cases and to determine the common cause (if there is one). I have no doubt that they’ll get to the bottom of this. I’ll bet that within a year we’ll know the cause and be close to either a cure or a preventative measure.
There were outbreaks of polio nearly every year throughout first half of the 20th century. Tens of thousands of children suffered various levels of paralysis before the Salk vaccine became available in 1955. These days the whole cycle of disease identification and research leading to a cure is much quicker.
Friday, February 28, 2014
Sunday, February 23, 2014
A National Human Feces Bank
You’ve heard of blood banks, but did you know that there is now a national non-profit banking system for human feces? “Why?”, you might ask. Well, it turns out that fecal transplants (either by nasoduodenal tube or by bowel lavage) are quite effective at treating recurrent infections of a particularly dangerous type of gastrointestinal infection.
The gastrointestinal infection in question is caused by a bacterium called Clostridium difficile. Under normal conditions, C. difficile is just one of thousands of types of normal bacteria that inhabit the gut. When most of the gut bacteria are wiped out, for example by the use of antibiotics, C. difficile may take over, producing a toxin that causes recurrent diarrhea. Infections by C. difficile kill more than 12,000 Americans a year, according to the CDC. C. difficile infections are not very responsive to antibiotics, making them difficult to treat.
Last year, research showed that fecal transplants were much more effective at treating infections of C. difficile than the best antibiotic treatment available. Apparently, by reintroducing a wide variety of normal bacteria back into the gut, fecal transplants prevent C. difficile from gaining a sufficient advantage to make the patient sick.
Until now, though, there was not been a source of standardized preparations of human feces. Patients had to rely on fecal donations from relative or friends, which some patients consider a little embarrassing. In addition, health professionals were on their own in terms of preparing and administering donated feces.
A national human feces bank seems like an idea that could work, despite the “yuck” factor. We’ll see how (or whether) it gains widespread support from patients and health professionals.
The gastrointestinal infection in question is caused by a bacterium called Clostridium difficile. Under normal conditions, C. difficile is just one of thousands of types of normal bacteria that inhabit the gut. When most of the gut bacteria are wiped out, for example by the use of antibiotics, C. difficile may take over, producing a toxin that causes recurrent diarrhea. Infections by C. difficile kill more than 12,000 Americans a year, according to the CDC. C. difficile infections are not very responsive to antibiotics, making them difficult to treat.
Last year, research showed that fecal transplants were much more effective at treating infections of C. difficile than the best antibiotic treatment available. Apparently, by reintroducing a wide variety of normal bacteria back into the gut, fecal transplants prevent C. difficile from gaining a sufficient advantage to make the patient sick.
Until now, though, there was not been a source of standardized preparations of human feces. Patients had to rely on fecal donations from relative or friends, which some patients consider a little embarrassing. In addition, health professionals were on their own in terms of preparing and administering donated feces.
A national human feces bank seems like an idea that could work, despite the “yuck” factor. We’ll see how (or whether) it gains widespread support from patients and health professionals.
Tuesday, February 18, 2014
Abnormal Sex Ratios in Two Post-Soviet States
I’ve blogged previously about abnormal sex ratios of newborns and the probability that sex-selective abortions are occurring in China and India. Now there’s evidence that sex-selective abortions are happening in several post-Soviet states as well. In Azerbaijan and Armenia, the newborn sex ratio of boys to girls for first-births is 1.13 and 1.38, respectively (the natural sex ratio is 1.05). If the first child is a girl, the sex ratio of the second birth in Armenia rises to an astonishing 1.54.
Health officials believe that the desire for male children is leading some parents to opt for an abortion when they learn that their current pregnancy is a girl. That trend gets even stronger after the couple already has a girl child. The ready availability of ultrasound to determine sex early in pregnancy now makes it possible to effectively abort a fetus that is not of the desired sex.
Different cultures have different feelings about the desirability of one gender over the other in their children. Governments and health officials will have their hands full either educating parents about the need not to abort certain fetuses, or creating legal barriers to it.
Health officials believe that the desire for male children is leading some parents to opt for an abortion when they learn that their current pregnancy is a girl. That trend gets even stronger after the couple already has a girl child. The ready availability of ultrasound to determine sex early in pregnancy now makes it possible to effectively abort a fetus that is not of the desired sex.
Different cultures have different feelings about the desirability of one gender over the other in their children. Governments and health officials will have their hands full either educating parents about the need not to abort certain fetuses, or creating legal barriers to it.
Friday, February 14, 2014
Breathing Xenon Gas May Improve Athletic Performance
Who would have thought that xenon, a rare and relatively inert gas, might boost athletic performance? The Russians, for one. Apparently they used xenon to improve the performances of some of their athletes in the 2004 and 2006 Olympic Games, according to an article in The Economist this month. And for now, it’s perfectly legal under the current rules of the World Anti-Doping Agency (WADA).
How does xenon gas exert its effect on athletic performance? It turns out that xenon boosts the body’s production of a protein called Hif-1 alpha, which in turn boosts the body’s natural production of erythropoietin, the hormone that regulates the body’s production of red blood cells. More red blood cells means more oxygen-carrying capacity and a better athletic performance, particularly in endurance sports. Cyclists have known about the endurance-enhancing effects of erythropoietin for years; witness the widespread use of injectable erythropoietin and ultimately the ensuing doping scandals (and the downfall of Lance Armstrong) in that sport.
The World Anti-Doping Agency (WADA) prohibits the use of injectable erythropoietin to boost athletic performance. But it is perfectly permissible to train at high altitude or to breathe a gas mixture low in oxygen to stimulate natural erythropoietin production. That did not go unnoticed by the Russians, who apparently developed guidelines for adding xenon to gas mixtures breathed by some of its athletes.
It’ll be interesting to see what position WADA takes on xenon gas, and whether or not it can prevent its use even if it wants to. Even a short exposure to xenon gas produces an elevation of erythropoietin concentration that remains long after the gas is gone. That would make enforcement of a ban difficult.
How does xenon gas exert its effect on athletic performance? It turns out that xenon boosts the body’s production of a protein called Hif-1 alpha, which in turn boosts the body’s natural production of erythropoietin, the hormone that regulates the body’s production of red blood cells. More red blood cells means more oxygen-carrying capacity and a better athletic performance, particularly in endurance sports. Cyclists have known about the endurance-enhancing effects of erythropoietin for years; witness the widespread use of injectable erythropoietin and ultimately the ensuing doping scandals (and the downfall of Lance Armstrong) in that sport.
The World Anti-Doping Agency (WADA) prohibits the use of injectable erythropoietin to boost athletic performance. But it is perfectly permissible to train at high altitude or to breathe a gas mixture low in oxygen to stimulate natural erythropoietin production. That did not go unnoticed by the Russians, who apparently developed guidelines for adding xenon to gas mixtures breathed by some of its athletes.
It’ll be interesting to see what position WADA takes on xenon gas, and whether or not it can prevent its use even if it wants to. Even a short exposure to xenon gas produces an elevation of erythropoietin concentration that remains long after the gas is gone. That would make enforcement of a ban difficult.
Saturday, February 8, 2014
HPV Vaccination and Sexual Behavior Among Young Women
A study published last month in Pediatrics reports that vaccination of adolescent women aged 13 – 21 with the human papillomavirus (HPV) vaccine does not change their attitudes toward safe sex or their subsequent sexual behavior. This study follows one published in 2012 that indirectly indicated the same thing, based on an examination of young women’s medical records (see "The HPV Vaccine and Sexual Activity".)
The current study involved 339 young women between the ages of 13 and 21 who received at least one dose of the HPV vaccine. Fewer than half of them were sexually experienced at the time of vaccination. Participants were asked (by questionnaire) about their sexual experience and their understanding of risk of sexual transmitted diseases (STDs) before, and again 2 and 6 months after, their first dose of the HPV vaccine.
Most of the young women correctly understood that the HPV vaccine did not change their risk of contracting STDs other than HPV. A few girls thought (incorrectly) that the HPV vaccine would reduce their risk of other STDs. However, these girls were not more likely to engage in sexual activity; in fact they were less likely to do so. Overall, there was no evidence that HPV vaccination leads to riskier sexual behaviors. Hopefully this study will convince parents who haven't had their daughters vaccinated yet because they thought that it might encourage promiscuity, to go ahead and allow their daughters to be vaccinated.
A word of caution. Six months is not a lot of time to assess changes in sexual activity in girls as young as 13. After all, most girls that age are not yet sexually active. It would be worth seeing if there are any changes in attitudes or sexual behavior further out; say, 5-10 years from now.
The current study involved 339 young women between the ages of 13 and 21 who received at least one dose of the HPV vaccine. Fewer than half of them were sexually experienced at the time of vaccination. Participants were asked (by questionnaire) about their sexual experience and their understanding of risk of sexual transmitted diseases (STDs) before, and again 2 and 6 months after, their first dose of the HPV vaccine.
Most of the young women correctly understood that the HPV vaccine did not change their risk of contracting STDs other than HPV. A few girls thought (incorrectly) that the HPV vaccine would reduce their risk of other STDs. However, these girls were not more likely to engage in sexual activity; in fact they were less likely to do so. Overall, there was no evidence that HPV vaccination leads to riskier sexual behaviors. Hopefully this study will convince parents who haven't had their daughters vaccinated yet because they thought that it might encourage promiscuity, to go ahead and allow their daughters to be vaccinated.
A word of caution. Six months is not a lot of time to assess changes in sexual activity in girls as young as 13. After all, most girls that age are not yet sexually active. It would be worth seeing if there are any changes in attitudes or sexual behavior further out; say, 5-10 years from now.
Tuesday, February 4, 2014
Keeping Nutrition Labels Fresh
The nutrition labels found on processed foods may undergo some modest changes in the future, according to a CNN news article last month. The labels haven’t really changed much in 20 years. Changes may include more emphasis on calories and certain types of fat and less on total fat content. Serving size is likely to become more prominent as well. And since many people don’t understand grams very well, some components (such as sugar) might be listed in teaspoons.
The FDA's goal is to make nutrition labels as useful and understandable as possible, while keeping the information in line with current dietary guidelines. For example, in the past decade or so it has become clear that “total fat” is not a very useful number since some fats are actually good for you while others are definitely not good. Future label changes are likely to emphasize the content of “bad” fats such as saturated fats, trans fats, and cholesterol. And in terms of weight management, total calories need special emphasis.
It’s all part of the plan to keep nutrition labels “fresh” and meaningful.
The FDA's goal is to make nutrition labels as useful and understandable as possible, while keeping the information in line with current dietary guidelines. For example, in the past decade or so it has become clear that “total fat” is not a very useful number since some fats are actually good for you while others are definitely not good. Future label changes are likely to emphasize the content of “bad” fats such as saturated fats, trans fats, and cholesterol. And in terms of weight management, total calories need special emphasis.
It’s all part of the plan to keep nutrition labels “fresh” and meaningful.
Monday, February 3, 2014
A New Way to Produce Fully Pluripotent Cells
Stem cells are undifferentiated cells that have the capacity to develop into many different types of adult cells. The best source of stem cells for research or medical treatment has always been stem cells harvested from very young embryos. The use of human embryos to harvest stem cells causes all sorts of ethical concern, of course, because human embryos must be sacrificed to harvest the cells. I doubt that anybody would actually prefer to harvest stem cells from embryos if there were another reliable source.
Some progress has been made in learning how to reprogram adult cells back into a “pluripotent” stage (capable of becoming multiple types of cells). Unfortunately, current techniques have not been able to produce pluripotent cells with virtually all of the properties of true stem cells.
Now, researchers in Japan and at Harvard University may have achieved a breakthrough of sorts. The researchers had been exploring ways to make adult cells revert to a pluripotent state closer to true embryonic stem cells. In a paper just published in Nature, the researchers exposed adult cells from mice to the stress of a solution with a high pH (a mildly acidic solution). Although many of the cells died, some of the ones that survived showed biochemical signs of having become pluripotent cells. More importantly, when the researchers injected these cells into embryonic mice, the cells grew and differentiated into virtually all types of adult cells, right along with the mice’s own cells.
It’s too soon to tell whether the technique would work with human cells. Nevertheless, the idea that exposing adult cells to a simple reproducible type of stress in the laboratory could cause them to revert to a pluripotent state very similar to embryonic stem cells is an exciting new concept. The day may yet come when human embryos are no longer needed as a source of stem cells. And that would definitely be a good thing.
Some progress has been made in learning how to reprogram adult cells back into a “pluripotent” stage (capable of becoming multiple types of cells). Unfortunately, current techniques have not been able to produce pluripotent cells with virtually all of the properties of true stem cells.
Now, researchers in Japan and at Harvard University may have achieved a breakthrough of sorts. The researchers had been exploring ways to make adult cells revert to a pluripotent state closer to true embryonic stem cells. In a paper just published in Nature, the researchers exposed adult cells from mice to the stress of a solution with a high pH (a mildly acidic solution). Although many of the cells died, some of the ones that survived showed biochemical signs of having become pluripotent cells. More importantly, when the researchers injected these cells into embryonic mice, the cells grew and differentiated into virtually all types of adult cells, right along with the mice’s own cells.
It’s too soon to tell whether the technique would work with human cells. Nevertheless, the idea that exposing adult cells to a simple reproducible type of stress in the laboratory could cause them to revert to a pluripotent state very similar to embryonic stem cells is an exciting new concept. The day may yet come when human embryos are no longer needed as a source of stem cells. And that would definitely be a good thing.
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