i on NIH Vodcast
January 8, 2010
“i on NIH” Vodcast Episode #0024
Welcome to “i on NIH”!
Featured in this month's episode are segments about research on a rare parasitic disease, and family history's link to type 2 diabetes.
From the national institutes of health in Bethesda, Maryland – America’s premiere medical research agency – this is "i on NIH"!
Covering health-research topics important to you and the nation, this public service vodcast is your information source from inside all 27 institutes and centers at NIH.
Half an hour, once a month, we’ll show you the excitement of advances and the important information that comes from medical research. And now, here’s your host, Joe Balintfy.
Host: Welcome to the 24th edition of I on NIH, thanks for tuning in. Coming up in this episode, we have a feature about a rare disease called Schistosomiasis including how the parasitic worms that spread the disease are grown in snails. Also, another eye-to-eye interview with Dr. Griffin Rodgers about risk factors for type 2 diabetes. But first, our news update. Here’s Harrison Wein from the NIH news-desk. What do you have for us this month, Harrison?
Harrison: Teen fitness linked to higher IQ and achievement, and how depriving yourself of certain foods may lead you to overeat.
Joe: So the first story is about the effects of fitness on the mind.
Harrison: Researchers looked at over 1.2 million young men born in Sweden between 1950 and 1976. All the men had physical fitness and intelligence tests at age 18 when they enlisted for military service.
The researchers compared this information to academic achievement and socioeconomic data from other national databases.
They found that cardiovascular fitness in the 18-year-olds was strongly linked to scores on intelligence tests. Muscular strength, on the other hand, showed little relationship to intelligence.
They then checked in a subset of twins to see if genes and upbringing were responsible, but the link between fitness and intelligence held in identical twins, too.
Joe: What about the effects later in life?
Harrison: The researchers found that the fit teens were more likely to get a university degree later in life. They also landed better jobs—with higher pay or management responsibilities—up to 36 years later.
Joe: So does this prove the link?
Harrison: No, this is an observational study. You’d have to do a very long, controlled experiment to prove that better fitness can do all this for you, but we do know that physical activity has many positive effects in the body. It lowers stress, it improves your heart and lung capacity, and helps your brain gets plenty of oxygen. So it’s not surprising that better fitness could have these effects on the mind.
Joe: Interesting. Another study might help explain why certain diets can backfire.
Harrison: Yes, many people try to lose weight by periodically forbidding themselves from eating certain foods. That might seem like a good idea: if you cut out foods you love, maybe you’ll find it easier to eat less overall.
Joe: That seems to make sense.
Harrison: Well, NIH-supported researchers recently found that rats given intermittent access to sugary food ate less of their normal food when the sweet food wasn't available, and overate the sweet food when it was available again. In other words, they were holding out for the good stuff. Sound familiar?
Joe: Yes, but what's been discovered here?
Harrison: Now, I won’t go into the heavy science here, but most research on overeating has focused on food's pleasurable effects—that’s called positive reinforcement. These scientists thought that what they were seeing in rats might be due to negative reinforcement.
That’s driven by the brain's response to fear, anxiety and stress. And it’s what’s behind withdrawal syndromes for drug of abuse. Could the same kind of thing happen when you deprive yourself of certain foods? Can the stress of not having these foods for a period drive dieters to overeat those foods later?
So the scientists tested a drug that blocks the action of CRF. CRF is a signaling molecule involved in the brain's response to this kind of stress. CRF has been tied to withdrawal syndromes for every major drug of abuse, including alcohol, nicotine, cocaine, opiates, amphetamines and marijuana.
Joe: Harrison, how did the scientists find this?
Harrison: So the team divided rats into 2 groups. One was fed alternating diets of 5 days of regular chow and 2 days of sweet chow. The other was given only regular food. All the rats could eat as much as they wanted and, after 7 weeks, the rats were given the CRF-blocker.
They found that CRF blunted the rats' bingeing. The diet-cycled rats ate more of the regular chow and less of the sweet food when it was available. The drug also blocked the rats' anxious behavior when their sweet food was withdrawn. It had no effect on the rats eating only normal chow.
The researchers then tested CRF levels in a region of the brain known to be involved in fear, anxiety and stress. The diet-cycled rats had much higher CRF levels when eating normal chow. Their levels were normal when they were fed sweet food. So these results show that withdrawal from tasty food, at least in rats, leads to an increase in stress.
Joe: So the idea is that people may be stressing themselves by cutting out certain foods?
Harrison: Yes, and essentially self-medicating that stress by overeating those foods when they finally let themselves eat them.
Now, let me repeat, this was a rat study and human eating behavior is a lot more complicated. But as we’ve reported in our other publication, "NIH News in Health," the best way to lose weight is to change your lifestyle so that you eat a healthier diet and get more physical activity. Studies have found that most dieting tricks can work in the short-term, but they often backfire for various reasons in the end-—and this is probably one reason.
Joe: Very good, Harrison. We'll have some more diet tips later in the program, but now where can people go to find out more on this research?
Harrison: Read about these and other NIH research studies in "NIH Research Matters." Go to the NIH home page and click the link on the right-hand side, under "In the News" that says, "eColumn: NIH Research Matters"
Joe: And what’s in this month’s health newsletter?
Harrison: January’s cover story is about the music and your health. And we also have a story explaining the facts about acne.
Joe: And where can people find those?
Harrison: That’s at news-in-health-dot-nih-dot-gov.
Joe: Thank you Harrison
Harrison: Thank you Joe.
Host: Schistosomiasis is a disease that rarely makes the news here in the U.S. But in many other parts of the world, people are all too familiar with it. In this segment, "I on NIH" highlights a unique resource that’s helping investigators learn more about schistosomiasis and devise potential ways to end it. Katie Rush has this report.
Katie: Scientists who study the neglected tropical disease schistosomiasis are relying on the National Institute of Allergy and Infectious Diseases, or NIAID, for an unusual research resource—snails. By providing this resource to scientists, free of charge, for use in their experiments, NIAID is helping scientists save money and combat a disease that is ravaging the developing world.
Dr. Lewis: This is a disease that does not grab the headlines very much. It’s a neglected disease; it infects the poorest of the poor. And we just think it’s a worthwhile thing to look at. It causes so many problems, and it predisposes people in the poorest countries to other infections as well.
Katie: According to the World Health Organization, at least 200 million people worldwide have schistosomiasis, and more than 700 million people live in endemic areas.
The cause?
Parasitic worms, which contaminate fresh water across the globe—primarily in Africa, but also South America, the Caribbean, parts of Asia and the Middle East.
When people come into contact with contaminated water, the worms burrow into people’s skin and make their way to blood vessels in the liver, intestines, or bladder.
There the worms can live for years, producing thousands of eggs that build up in the body and cause serious pain and internal scarring.
Currently, no vaccines exist to prevent schistosomiasis. There are drugs available, but they can’t prevent reinfection.
For scientists to tackle schistosomiasis, then, they must learn more about the parasites that cause the disease and their complex life cycles.
What they know already might surprise you:
Before the worms ever make it inside humans to lay eggs, they must first spend time maturing in an intermediate host—in this case, specific species of snails. Studying the parasites in snails could yield possible interventions to stop the disease.
Dr. Knight: If we can look at the molecular interaction of the parasite in the snail, we might be able to actually translate that to how we relate to the parasite ourselves.
Katie: But maintaining colonies of snails for use in experiments is no easy task. That’s where NIAID’s Schistosomiasis Resource Center comes in.
McGugan: The problem is, if investigators want to actually look at different stages of the disease, of the parasite, they’d have to maintain the entire operation in their own lab. Which is not only expensive to maintain, but also requires a level of expertise that not every lab has. So back in the 60s, the NIH had the foresight to fund a contract so these life cycle stages could be maintained so researchers could tap into that without maintaining these life cycle stages in their own labs. So by doing that, researchers are able to use their research dollars in other ways.
Katie: The Schistosomiasis Resource Center supports 90 labs around the world by providing supplies and training, and researchers depend heavily on that support. Last year, the Center sent out about 45,000 snails to researchers for use in experiments.
And since its founding, the Center has made possible thousands of publications on schistosomiasis research.
Scientists use resources from the Center for a variety of experiments. Some scientists are working to develop vaccines or better drugs to prevent or treat infections in people.
Other scientists are focused on blocking transmission of the parasite in the snail so that it never reaches humans in the first place. Ultimately, a combination of approaches may be most effective in solving the problem.
Dr. Lewis: People are looking at various places around the cycle to break it. That’s why people are interested in treating people; if all the people were treated, no eggs would be contaminating the environment. If all the snails were killed in an area, they could not transmit. So it’s research into all of these various phases that’s important—and it may be a combination of all of these—that eventually reduces it.
Katie: But for some people, the most intriguing research questions about schistosomiasis are the most basic ones:
Dr. Knight: Why are there parasites? What makes them parasites? What are their basic needs, and why do they exist? To me, you can’t separate it from the entire biological questions here. Precisely the big question and the most interesting question. And if we can understand that, can you imagine: to rid the world of these parasites for good?
Katie: In the meantime, the Schistosomiasis Resource Center continues to supply critical resources to the scientific community and help new researchers enter the field.
Increasingly, researchers are recognizing that schistosome infections share symptoms of many other diseases, too, and that basic research discoveries about schistosome infections may have important crossover applications for asthma, fibrosis, and other conditions as well.
Katie: For more information about schistosomiasis research and other research resources at NIAID, visit: www.niaid.nih.gov.
For "I on NIH," this is Katie Rush.
Host: Thank you Katie. A couple episodes ago, we talked to Dr. Griffin Rodgers, director of the National Institute of Diabetes and Digestive and Kidney Diseases about the seriousness of type 2 diabetes. In this next interview with Dr. Rodgers, we learn more about the risk factors – including family risk – as well as a condition called pre-diabetes. We started though by getting some background, asking:
Q: How prevalent is diabetes among Americans?
Dr. Rodgers: Well, there are approximately 24 million Americans over the age of 20 that have diabetes in this country, and of that number, roughly six million of them are unaware that they have diabetes. Now, more sobering though, is that there are 57 million Americans, again, over the age of 20, that have a condition called pre-diabetes.
Pre-diabetes is a condition in which the blood sugar is higher than normal, but not high enough to actually give one a diagnosis of diabetes. People are at greater risk for having type 2 diabetes, or pre-diabetes rather, or people from certain racial and ethnic groups, and certainly one is at higher risk if one has a brother or sister or parent that has a diagnosis of diabetes.
Q: What are the symptoms of diabetes or pre-diabetes – how would someone get diagnosed?
Dr. Rodgers: Well, oftentimes, pre-diabetes may be asymptomatic, and that’s why it’s so important to know whether one has a family history of diabetes. So if one has a parent or a brother or a sister, or a first degree relative like an aunt or uncle that has a diagnosis of diabetes, that’s important to know, and that should be relayed to one’s health care professional.
For certain other racial and ethnic groups, for example, African-Americans, Hispanic and Latinos, Asian-Americans, Pacific Islanders, Native Americans and Alaska Natives who are at higher risk for having pre-diabetes and that, obviously, by history and physical examination, your health care provider will know that.
But it’s also important to realize that in this country, about nine percent of women who go through a normal pregnancy will develop what’s called gestational diabetes, and not only as a mother who has gestational diabetes herself at risk for developing diabetes later on in life, but the child of—the infant born from that mother is also at higher risk of developing diabetes sometimes later in their life, but also developing obesity. And so family history is important, being from a certain racial and ethnic group is important, certainly patients who are inactive or overweight are at greater risk, individuals who are older, for example, over 45 years of age, are also at higher risk of having pre-diabetes, and those are important factors that should be discussed with one’s health care provider.
Q: If someone has one or more of those risk factors, what can they do to prevent or delay the onset of type-2 diabetes?
Dr. Rodgers: Well, a very important study done, the Diabetes Prevention Trial, showed that [many of these] individuals who are at high risk for developing diabetes who had pre-diabetes, many of these individuals were overweight. They were from these racial and ethnic groups that I just discussed. They generally had little in the way of physical activity previously. The study showed that with modest lifestyle intervention—modest lifestyle intervention meant generally losing five to seven percent of one’s body weight.
So for example, if you were a 200-pound individual, losing just 10 or 14 pounds through a diet change, which reduced the number of calories and the amount of fat, for example, and also stress physical activity, about 30 minutes a day of brisk walking, five days a week, one could achieve that reduction in the amount of weight one has, and that translated to a delay in the development of type 2 diabetes compared to the control group.
So there are action steps that one can take, fairly modest lifestyle changes, if one is in these high risk groups, one has a family history, they should let their health care provider know about it, have them tested to determine whether they have pre-diabetes, and there are positive steps that one can take, modest steps that one can take to prevent or delay the onset of diabetes.
Q: Is there more information available about diabetes, pre-diabetes and family risk?
Dr. Rodgers: Sure, the National Diabetes Education Program, or NDEP, has a free booklet called "Your Game Plan to Prevent Type 2 Diabetes: Information for Patients." And they can get this information through visiting our Web site at NDEP—yourdiabetesinfo.org, or they can call a toll free number, 1-888-693-NDEP, and let me say that again. It’s 1-888-693-6337.
Host: Thank you Dr. Rodgers. And that’s it for another episode on I on NIH. If you’d like to see or forward individual segments from this program, they’re available on YouTube. Check out the NIHOD channel. Thanks for tuning in and please watch again next time. For I on NIH, I’m Joe Balintfy.
Narrator: "I on NIH" is a public service vodcast from the Department of Health and Human Servives. Produced by NIH News Media Branch, of the Office of the Director, Office of Communications and Public Liaison. Thanks for tuning in. We’ll be back again next month with another episode of "I on NIH."
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