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December 17, 2010
NIH Podcast Episode #0124
Balintfy: Welcome to episode 124 of NIH Research Radio with news about the ongoing medical research at the National Institutes of Health – the nation's medical research agency. I'm your host Joe Balintfy. Coming up in this episode, a special in-depth feature on the new food allergy guidelines; and our series continues on nanotechnology and cancer: in this episode a look at imaging. But first, a program reminder.
Happy Holidays from NIH Research Radio! Two end-of-year program notes for you: our News Update is taking a break, and we’re skipping New Year’s Eve. Episode 125 due Friday, December 31st will be available on Friday, January 14th. We will return to our regular, every-other-Friday schedule on January 14th. So be sure to tune-in in the New Year, and thanks for listening. Happy Holidays again from NIH Research Radio!
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Food allergy guidelines
Balintfy: Back in episode 106 of the NIH Research Radio podcast in March, we talked to Dr. Mathew Fenton chief of the Asthma, Allergy and Inflammation Branch at the National Institute of Allergy and Infectious Diseases. We talked about the food allergy guidelines. At the time, the guidelines were open for public comment. Now, as of December 6, the Guidelines for the Diagnosis and Management of Food Allergy in the United States: Report of the NIAID-sponsored Expert Panel have been released. So for this special feature, we’re talking with Dr. Fenton again, as well as Mary Jane Marchisotto, executive director at the Food Allergy Initiative and Dr. Robert Wood, chief of pediatric allergy and immunology at Johns Hopkins. We start with Dr. Fenton and a reminder of what the food allergy guidelines cover and who are they for:
Fenton: Well the guidelines are intended to be a single, one-stop shopping resource for physicians who work in a variety of clinical subspecialties who want to diagnose and manage their patients with food allergy.
Balintfy: And there are a lot of Americans who are food allergy patients, says Mary Jane Marchisotto at the Food Allergy Initiative.
Marchisotto: We want people to understand that food allergies are a major national health problem that affect more than 12 million Americans, including roughly 3 million children.
Balintfy: Dr. Robert Wood, a member of the expert panel that wrote the guidelines, currently manages patients with food allergy (and conducts NIAID-supported food allergy research), and has a food allergy himself. He points out that food allergy incidence may be on the rise:
Wood: There’s lots of evidence that it’s increasing quite rapidly. So we think that it’s probably somewhere around twice as common now as it was 20 years ago.
Balintfy: And is the severity of food allergy also increasing according to Dr. Wood?
Wood: We have a notion that it is, but that’s not something we have studies to really document. Our feeling thought is that it’s not only more common, but that it has become more severe.
Balintfy: The severe symptoms associated with the most severe forms of food allergy, symptoms such as anaphylaxis, can be life-threatening. In fact, food allergy is the most frequent single cause of emergency room visits for anaphylaxis and accounts for 34 to 52 percent of these visits. The Food Allergy Initiative’s Marchisotto sites a survey of elementary school nurses it identified food allergy as one of the largest problems they deal with in the school setting, surpassing even juvenile diabetes.
Marchisotto: About a quarter of food allergy-related emergency room visits involve children under the age of five. People don’t understand that.
Wood: And people have almost no appreciation for how a food allergy impacts on day-to-day life.
Balintfy: Dr. Wood at Johns Hopkins:
Wood: And we now have studies that show, for example, that having a severe food allergy has a greater impact on a child’s quality of life than having diabetes, or having rheumatoid arthritis, diseases that we think of as being far more severe. It turns out that food allergy runs your life on a day-to-day basis, far more than those severe diseases do.
Fenton: And it’s important to point out with food allergy that there currently is no actual treatment for the disease. You can treat the symptoms of food allergy, but management primarily involves avoiding the allergen.
Balintfy: Dr. Fenton adds that an underlying goal of the food allergy guidelines is to have a single set of criteria that physicians can use when diagnosing and managing the disease.
Fenton: One of the difficulties has always been that the symptoms of food allergy can mimic many other diseases, such as food intolerance, and it’s important for the physician to be able to provide a differential diagnosis for these diseases. And as we looked into the question originally when we started this project two years ago, to our surprise, physicians in different specialties were using even basic definitions for what was food allergy. And then it got worse from there; everyone used different methods to diagnose the disease, or to recommend methods to manage the disease.
Wood: And there was real concern that if a bunch of food allergist wrote this, that we would give a biased or inaccurate picture about the whole scope of food allergy. So the goal was to bring experts from a variety of different disciplines. So the expert panel was made up, not just of allergists, but of pediatricians, gastroenterologists, pulmonologists, dermatologists, emergency room physicians, and everyone bought their own unique expertise, their own unique opinions. And the real strength of the guidelines was the ability to actually put together all of these different opinions and expertise. The other real strength of the guidelines is that in every way possible, it was evidence-based. So there was an incredibly detailed look at the literature, at the studies that had been done. And then all of those then were presented back to the expert panel to break down and put into the guidelines.
Marchisotto: We believe that the guidelines will have a major impact on the way medical practitioners from a variety of disciplines diagnose and treat patients with food allergy.
Balintfy: The Food Allergy Initiative’s Marchisotto and Drs. Fenton and Wood, all agree that while the guidelines were designed by experts for experts, food allergy patients will be the ones benefiting. Dr. Fenton explains that as part of the project, there will be companion documents to the food allergy guidelines:
Fenton: One is a patient- and family-friendly synopsis of the guidelines. So, the idea there is to provide information for patients and families on what the guidelines mean for them. How can they best understand how to work with their physician by understanding what’s in the guidelines and what it means for them?
Balintfy: Marchisotto adds that up-to-date, easily understandable information will enable people with food allergies to become active members of their own healthcare team.
Marchisotto: Diagnosing and living with food allergies can be a long and complicated process. We believe that it’s important that, when patients and families speak with their physicians, they know what questions to ask and what to expect.
Balintfy: Dr. Fenton hopes that the synopsis will be a great tool for patients to help them work more effectively with their physician.
Fenton: The impact here for patients, I think, can be quite large because even now, 50 to 90 percent of self-reported cases of food allergy are actually not food allergy. By the time they’ve been thoroughly diagnosed, and there’s been laboratory workups, it turns out to be something different. Maybe a gastrointestinal disease, maybe a food intolerance, but not actual food allergy. So it’s important for patients to understand that this is a complicated disease and its symptoms can mimic other diseases as well.
Balintfy: Dr. Wood concurs, saying the main audience for the guidelines is the clinician, whether allergists, pediatrician, family practitioner, or dermatologist, but the guidelines will help everyone.
Wood: In the end, the public will benefit far more than the clinician because they are going to be provided with better care. They are going to have complete access to this. And we find in much of medicine, maybe food allergy more than any other, that the public is extremely well-educated and will use this document for their own education. And in many cases, I am sure they’ll go back and educate their clinician about what they read in the guidelines.
Balintfy: But Dr. Wood cautions there are some weaknesses to the guidelines.
Wood: The weaknesses all come from the lack of evidence. So if you read the guidelines carefully, there are many, many recommendations that are based on expert opinion primarily or solely. So when you take something like anaphylaxis, we know what anaphylaxis is, we think we know how to treat it, but studies are not generally done to say, do you give epinephrine soon, or sooner, or wait until later, because the risk of doing that kind of study is potentially leading to a fatality. So there’s lots of places where we had to rely on the expert opinion of the panel. And the weaknesses really came from some of the gaps in research that has been done or not done in the past.
Balintfy: Dr. Wood adds that the food allergy guidelines will have a positive impact, and may help open the door for a cure in the future.
Wood: Well, they are going to have an immediate impact on diagnosis because a—you know, clear recommendations have now been provided on the right way to diagnose food allergy. And one of the real dilemmas in caring for patients with suspected food allergy is making the right diagnosis. And it turns out that the diagnostic tests we have are not terribly good tests in many instances, so using them to their maximum advantage is to everyone’s best interest.
The future, in terms of real treatment and a cure, is something that the guidelines could not take on. But I think that the added public awareness that the guidelines will bring to food allergy are going to have impact on funding agencies and public policy that in the long run will lead to a cure much quicker than it would otherwise have happened.
Balintfy: As for the future of the guidelines, because there are no cures for food allergy currently, Dr. Fenton says updating the guidelines is up in the air. But changes that may happen over the next 10 years may be reason to modify them.
Fenton: There have been tremendous advances in immunotherapy, the ability to manipulate the immune system to make the immune system tolerant to foods to which you are allergic. And there have been many published clinical trials showing the benefits of this type of therapy, but none of these studies have gotten to the point of requesting FDA approval so that this can become a marketable therapy.
Balintfy: Dr. Wood says research is closing in on a cure and progress made in the last four years has been better than he would have predicted.
Wood: The studies are still small. The results are still very preliminary. But the fact is that there are people being cured of food allergy, and that’s something that we didn’t know was possible just five years ago. So we’re very optimistic. We think that there are ten more years of work to be able to perfect this system, but we do think, based on the studies that we have done so far, that this is potentially the approach that will lead to a cure of food allergy. And I say potentially because it may be that in ten years, we’ve learned better and safer ways to do this. So other approaches are under active investigation as well. And in the end, what we’re looking for is obviously the one that works the best, but also the one that will be easiest and safest for the patient.
Balintfy: The guidelines have been published online in the December 6 issue of the Journal of Allergy and Clinical Immunology. Dr. Fenton:
Fenton: And that document in manuscript form in the journal is going to be about 45 pages. What we did also generate is a summary of the guidelines, which is about 14 pages. And that document certainly can be rolled up and stuck in a pocket quite easily.
Balintfy: Dr. Wood says most clinicians are desperate for good information on food allergy.
Wood: And even though there may be some things in here that will affect the way they practice in a way that they are not immediately in agreement with, the vast majority are going to be thrilled to have something they can turn to. And the way that the guidelines were constructed, it was really in a very practical user-friendly kind of format. So a clinician will be able to quickly open the guideline to, say, the section on anaphylaxis or the section on diagnosis, and in a matter of minutes put their finger on information that might have taken them hours or weeks to find before.
Balintfy: Thanks to Dr. Robert Wood at Johns Hopkins, Mary Jane Marchisotto at the Food Allergy Initiative, and Dr. Matthew Fenton at NIAID. For more information on the food allergy guidelines, visit the website www.niaid.nih.gov.
Coming up, our series on nanotechnology and cancer continues. That’s next on NIH Research Radio.
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Nanotechnology and cancer: imaging
Balintfy: In this part of our series on nanotechnology and cancer, we talk to Dr. Sam Gambhir, professor of radiology and bioengineering at Stanford University about imaging. First, Dr. Gambhir, what are the more common imaging methods used today to detect and treat cancer?
Gambhir: The more common imaging methods that are used to both detect cancer, stage it, monitor response to therapies, and then also monitor for recurrence are predominately positron emission tomography, or PET scanning; single photon emission computed tomography, or SPECT scanning; and then magnetic resonance imaging, or MRI; as well as computed tomography, or CT scanning. So PET, SPECT, MRI and CT are by far the most dominant players in most cancer, and then ultrasound is also playing an important role.
Balintfy: How effective are these techniques?
Gambhir: They have different accuracies depending on what type of cancer you are studying, where in the body you are looking, whether you are looking at the primary cancer or its metastases. In general, they are quite useful clinically, but we know we need to do better.
The problem is these technologies are still not perfect. So if there’s very few cells that have metastasized away from the primary at a distant site, the PET scan might miss them. It might say that there is nothing there when in fact there is something there. So especially micro metastasis, as they are called, smaller amounts of tumor burden, are the hardest things for all these technologies to solve.
Balintfy: Can nanotechnology help?
Gambhir: Yes, so the hope is that, that nanotechnology and nanoparticles coupled with the right imaging instruments, whether they be PET, whether they be MRI, whether they be multimodality imaging instruments like combined MRI PET, all those will benefit from nanotechnologies in the future.
Balintfy: How does imaging with nanotechnology, compare to imaging using molecules? Are there advantages to using nanoparticles Dr. Gambhir?
Gambhir: Yes, so in molecular imaging, molecules are injected into the body that go and home in on other molecules, molecules that might be indicative of cancer. But once they home in on those molecules, they have to produce a large signal that we can detect outside the human body. So nanoparticles are able to sometimes serve as very good amplifiers. They amplify the signal much more so than a small molecule might or even a protein or a biologic might. So one big advantage is the signaling power.
Another advantage is that as we try to use nanoparticles because they have more landscape, they are larger, we can functionalize them with different molecules so they have multiple functions.
A third big advantage that nanoparticles offer is that they end up sometimes being multimodality competent. That is, you can make a nanoparticle so that it produces a signal both for an MRI camera, and for a PET camera, and for a third modality. That multimodality feature of a particle is harder to do when the particle is not a nanoparticle and is a small molecule.
And finally, the fourth big advantage of nanoparticles is that they themselves can help be both a diagnostic and a therapeutic. So if you are going to bother to image a tumor and send a particle in that can go hunt down an abnormal protein in a tumor cell, why not also have the particle be a therapeutic as well, because there is obviously similar goals between diagnosing and therapy or treating. So this whole field of theranostics, the merger of therapeutics and diagnostics, so-called theranostics, has the potential to benefit a lot from nanoparticles that serve both as the diagnostic or imaging agent and as a therapeutic. And that is the one other major advantage nanoparticles have over molecule types for molecular imaging.
Balintfy: What example would you share as a recent nanotechnology breakthrough in cancer imaging?Gambhir: We have, in development as part of our own nanocenter, particles that are made out of gold that go into the bowel to detect colorectal cancer. But the way the gold helps us to detect the colorectal cancer is that we use a fundamentally new way of imaging called Raman spectroscopy, and the gold acts as an amplifier to produce a very heavy or strong Raman signal from the gold particle after it has latched onto a colorectal cancer. So right now, flat lesions especially might be entirely missed by the endoscopist who might be doing screening for colorectal cancer, but by having the gold nanoparticles light up literally where the cancer, including flat lesions, might be hiding in the bowel, now the hope is that the endoscopist will be able to act on a lesion they would have otherwise missed.
So this strategy, in this case, involves a nanoparticle, one made out of gold. It involves an imaging strategy, which is not MRI, not PET, not SPECT, not CT, not ultrasound. It is called Raman imaging, and really this imaging is only possible with a nanoparticle. That is, without a nanoparticle, Raman imaging is just too insensitive. So there are many examples like this where the nanoparticles are enabling significant signal and actually enabling entirely new kinds of imaging technologies that can work with the human body that previously could not have worked because the nanoparticles were not there to produce the right signals for those imaging technologies.
Balintfy: Can you share some other examples Dr. Gambhir?
Gambhir: Yes, so the other—so the Raman imaging is one. The second I would say is nanoparticles for photoacoustics. In photoacoustic imaging, light goes into the body, red shifted light that can penetrate deeply, that light interacts with a nanoparticle, and the nanoparticle then slightly heats, not enough to cause any damage, but slightly heats. And that heating produces a pressure wave and therefore sound. So light in, sound out. And a nanoparticle can be designed so that it is very good at absorbing the light and very good therefore at producing sound. And the nanoparticle can be functionalized to go find tumors. Gold, as it turns out, is also a very good material for absorbing light and producing a strong photoacoustic signal. Also carbon-based molecule like nanotubes are very black and dark; they do a good job of absorbing light and therefore heat to produce sound. And several other molecule nanoparticle strategies are on the horizon for this new emerging area of photoacoustic imaging.
And these likely will translate in the clinic with applications of prostate cancer imaging, breast cancer imaging, things where you aren’t trying to go too deep, but deep enough where light can go in and sound come back out, letting you get much better spatial resolution, much better sensitivity to detect smaller tumors than what is what is possible with other current imaging technologies.
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Balintfy: Thanks to Dr. Sam Gambhir at Stanford University. For more information on nanotechnology and cancer, visit the website, nano.cancer.gov. This nanotechnology series will continue next episode when we’ll talk more about nanotechnology and diagnostics.
“If you want to use a Christmas tree analogy, they’re little ornaments, they’re balls, they’re little nanoclusters in our case of gold and then we use the gold as a catalyst.”
But remember, as mentioned at the beginning of the program, NIH Research Radio is taking a break: our next edition, episode 125 scheduled for Friday, December 31 won’t be available until Friday, January 14.
For now that’s it for this episode of NIH Research Radio. Please join us again on Friday, January 14 when our next edition will be available. As usual, if you have any questions or comments about this program, or have story suggestions for a future episode, please let me know. Best to reach me by email–my address is jb998w@nih.gov. I'm your host, Joe Balintfy. Thanks for listening.
Announcer: NIH Research Radio is a presentation of the NIH Radio News Service, part of the News Media Branch, Office of Communications and Public Liaison in the Office of the Director at the National Institutes of Health in Bethesda, Maryland, an agency of the US Department of Health and Human Services.
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