February 8, 2008
NIH Podcast Episode #0051
Balintfy: Welcome to the 51st episode 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 edition we’ll have a report and talk more with Dr. Griffin Rodgers about chronic kidney disease, and have an interview with the director of NIH about biomedical imaging. But first a story about how some brain tumors grow. That's next on NIH Research Radio.
(BREAK FOR PUBLIC SERVICE ANNOUNCEMENT)
Researchers Uncovered an Error in Immature Brain Cells which may Promote the Growth of Some Brain Tumors
Balintfy: Researchers have uncovered an error in immature brain cells that may promote the growth of some brain tumors according to a study by the National Cancer Institute and the National Institute of Neurological Disorders and Stroke. Wally Akinso reports:
AKINSO: In various laboratory experiments, a breakdown in proper cell development has been shown to cause brain-specific stem cells to become starter seeds for aggressive brain tumors called glioblastoma multiforme. Dr. Howard Fine, Chief of the Neuro-Oncology Branch at the NCI's Center of Cancer Research, talks about the clinical context of the findings.
FINE: The more we understand the mechanisms by which normal cells become tumor cells and how they depend on these abnormal mechanisms then we can develop new treatments, specifically new drugs to target these abnormal pathways. Hopefully in these particular cases make these tumor stem cells behave more like normal stem cells and make them mature and differentiate at which point they would know longer be able to grow and cause tumor growth.
AKINSO: According to Dr. Fine, many researchers have come to believe that the activity of a small group of stem-like tumor starter cells, or tumor-initiating cells with stem like properties may be one of the main reasons that cancer develops. This is Wally Akinso at the National Institutes of Health, Bethesda, Maryland.
Chronic Kidney Disease-Cardiovascular Disease Link
Balintfy: Though February is American Hearth Month, it’s also an important time to talk about kidney disease. Dr. Griffin Rodgers, Director of the National Institute of Diabetes and Digestive and Kidney Diseases explains.
Rodgers: There is a very important connection between chronic kidney disease or CKD and cardiovascular disease. People with CKD are more likely to develop cardiovascular disease than people without CKD.
Balintfy: Dr. Rodgers warns that the connection between chronic kidney disease and cardiovascular disease goes both ways.
Rodgers: People with CKD have a higher risk of developing cardiovascular disease,. And the reverse is true as well: people with cardiovascular disease have a higher risk of chronic kidney disease. High blood pressure and diabetes damage the small vessels in the kidneys and elsewhere in the body, including the vessels that supply the heart.
Balintfy: Dr. Rodgers says it’s important to be screened for chronic kidney disease.
Rodgers: CKD is often called a “silent” disease because many people don’t realize that they have chronic kidney disease until their kidneys have almost completely stopped working. NIH recommends that people who have diabetes, high blood pressure, cardiovascular disease, or a family history of cardiovascular disease work with their health care provider to monitor their kidney health. Blood and urine tests are the only ways to know if early CKD is present.
Balintfy: Dr. Rodgers adds that people with CKD can take important steps to keep their kidneys, heart and blood vessels healthier longer.
Rodgers: These steps are, for example, maintaining their blood pressure at 130/80 or below. An important way of doing that is to limit sodium intake. Some drugs not only lower blood pressure and protect the kidneys and the heart. If diabetes is present, for example, controlling the blood sugar is a way to not only maintain the integrity and viability of kidneys, but also the heart and blood vessels. Maintaining a healthy body weight. Maintaining a healthy lifestyle with exercise. Quit smoking. And controlling cholesterol. And although aspirin is quite effective in reducing the risk of cardiovascular disease, in patients that have CKD there is an increased risk of them developing abnormal bleeding complications. So it’s very important for one to check with one’s health care provider before taking aspirin in this context.
Balintfy: Up next, more discussion with Dr. Griffin Rodgers about the risks and connection between chronic kidney disease and cardiovascular disease.
(BREAK FOR PUBLIC SERVICE ANNOUNCEMENT)
Dr. Griffin Rodgers Interview
Balintfy: We’re talking with Dr. Griffin Rodgers Director of the National Institute on Diabetes and Digestive and Kidney Diseases. Can you give us some more background on chronic kidney disease?
Rodgers: Well, most people have two kidneys and they’re located near the middle of the back, just below the ribcage on each side of the spine. Every day, the healthy kidneys filter about 200 quarts of blood and removes about two quarts of waste and extra water to in the form of urine. Now, the kidneys really play a significant role in not only the elimination of this waste, but also in controlling blood pressure, in making red blood cells and in maintaining healthy bones. Each kidney contains about a million tiny filters made up of blood vessels. And kidney disease or chronic kidney disease occurs when these blood vessels become damaged. Over time, more and more of these vessels and filters become damaged, and eventually the kidney looses its filtering capabilities. When it does that, one has to either undergo dialysis, which is an artificial form filtering the blood, or at that stage require a kidney transplant to maintain the filtering ability.
Now the most common cause of chronic kidney disease or CKD in this country are diabetes and high blood pressure, and so people with these diseases should be regularly tested for the presence of chronic kidney disease. And the earlier one determines whether one has CKD or not, then steps can be taken to reduce the risk of further damage.
Balintfy: Is the increased risk of cardiovascular disease due to kidney disease or to the conditions that lead to CKD, specifically diabetes and high blood pressure?
Rodgers: Well we’re still learning more about the interaction of these diseases, but no doubt CKD is an important risk factor, an important independent risk factor for developing cardiovascular disease. Traditional heart disease risk factors, such as hypertension, smoking, diabetes and older age, are very common among people with CKD. In fact, nearly all people with CKD have high blood pressure, a known risk factor for the development and progression of cardiovascular disease. For many patients, the earliest sign of CKD is protein in the urine; it is also a predictor for cardiovascular disease. People with CKD are also more likely to have the metabolic syndrome, which is a constellation of symptoms – obesity, blood sugar poor control, high blood pressure some of the cardiovascular symptoms as well.
Balintfy: Does high blood pressure lead to CKD or vice versa, or is that an oversimplification?
Rodgers: No you’ve hit the nail right on the head. What happens is the kidney is filtering this blood. Now as you, the high blood pressure which is sort of pushing through these filters ultimately can damage those filters. And as you loose one, and then two and then multiple of these filters, you’re not allowing the blood to be filtered at all. And thus, the hypertension remains present but one now begins to increase the levels of toxins in the blood, increases the amount of sodium that’s retained in the blood and those all contribute to further increase the blood pressure and subsequently further damaging those few remaining filters that are in the kidney. So one leads to the other, but the presence of the other can have a kind of spiraling effect. The same is true of diabetes.
Balintfy: What are some of the things NIH doing to explore the connection between CKD and CVD?
Rodgers: Many researchers funded by the NIH at university and academic and medical centers throughout the U.S. are working on CKD and cardiovascular disease and their connection. For example, the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) is sponsoring a major study—the Chronic Renal Insufficiency Cohort or CRIC study—is a study to identify the factors linked to rapid decline of kidney function and the development of cardiovascular disease. CRIC is following 3,000 adults for seven years. And all study participants have mild to moderate CKD as an important entry criteria. We believe that a subset of these patients will go on to lose kidney function more rapidly than others, and develop cardiovascular disease more rapidly than others.
We are also partnering with the National Heart, Lung, and Blood Institute (NHLBI) on a study of Systolic Blood Pressure Intervention Trial: the SPRINT study. I mentioned previously that we recommend that patients that have chronic kidney disease maintain a blood pressure at a level of 130/80. But in this group, in this study that we’re performing in collaboration with the Heart Lung and Blood Institute, we’re really going to target a lower number 120 or lower to see whether we lower it by that amount we can diminish the decline in loss of kidney function as a function of time.
Balintfy: Are there other NIDDK research avenues that are addressing the CKD connection with cardiovascular disease?
Rodgers: Well, you know there’s a rise in this country in obesity and that’s contributing not only to diabetes, hypertension, but also cardiovascular disease and chronic kidney disease, or CVD. We need to learn more about the relationships between these conditions, how they affect each other, and how we can prevent and treat them. At NIDDK we are investing in a broad range of studies from both basic biology to clinical trials about diabetes, obesity, and CKD.
We are also committed to rapidly translating this new knowledge into proven therapies that benefit patients. We have a National Kidney Disease Education Program, NKDEP, is educating the public, health professionals and laboratory professionals on the best ways to prevent, detect and treat CKD and kidney failure. And we’re working with the Centers for Disease Control and Prevention to reduce the morbidity and mortality associated with diabetes through a related, actually the parent of the NKDEP is the National Diabetes Education Program.
We are partnering with other Institutes at the NIH in particular the Hearth Lung and Blood Institute, the National Cancer Institute, NCI, and the National Institute of Child Health to address the nationwide childhood obesity epidemic through the We Can program. We Can is an acronym that stands for Ways to Enhance Children's Activity and Nutrition. And so we believe that if we intercede and interject very early on in the process of obesity leading to diabetes and high blood pressure and that ultimately leading to chronic kidney disease that early prevention is really the best way to go here.
Balintfy: For more information about CKD, visit the National Kidney Disease Education’s Website at www.nkdep.nih.gov or call toll free, 1-866-4-KIDNEY.
Balintfy: For this next interview, I am pleased to have Dr. Elias Zerhouni, Director of the National Institutes of Health. A leader in the field of biomedical imaging, we talked about the importance of CAT scans, MRI’s and the science of imaging in general.
Dr. Zerhouni, what do you think is the most important information the American public should understand about biomedical imaging today?”
Zerhouni: I think that imaging is really a science that has come into its own, not only over the past 30 years, but it’s currently undergoing a tremendous revolution. The reason is that it’s addressing a very fundamental need in medicine. In the past, to find out what was going on in the body, you had to do surgery. So in many ways, the dream of scientists in imaging like myself was, how can you peek into the human body without destroying it, so it’s nondestructive? And that was the impetus for my research in CAT scanning and MRI over the past 30 years and it has made a revolution in how we diagnose disease, how we treat disease. But going forward, what people are realizing is that in biology, interactions, whether it be DNA or RNA and molecules and another one, the cell within the cell, or an organelle within a cell or a cell with a cell or within tissues, all of these interactions are localized in space. And to extract that information you need what we call imaging. So, imaging is going to work over the next 40 years to try to unravel the mysteries of how molecules interact, how cells interact, how tissues interact. Imagery is going to be even more important not just for medical applications, for fundamental research and for understanding biology.
Balintfy: What is your view about the value of CT scanning specifically in detecting certain cancers?
Zerhouni: So, basically when you look at an imaging technique, essentially what you have is a way of looking at biology, looking at anatomy and structure and function in an indirect way. And whenever you have an indirect technique, what you really want to know is how accurate it is. And you don’t want too many false negatives, where you are missing something, or false positives, where you are seeing something that you think is a disease. And that’s why CAT scanning has been developed to detect lesions in organs like the lung or the rest of the body. And we’re developing other tests, like ultrasound for example, to look at interuterine pregnancies and so on. So, the value has increased over time. Mammography to look at early cancers.
But every time you do this you have to be very careful, because the value of the test depends on how accurate it is, and to find that out you need to really do very rigorous trials. It’s not enough to believe that something works; you have to prove that it works. So that’s what I think is important here, is we have to do that research to provide the American public with the very, very scientific evidence-based answer rather than opinion-based answer.
Balintfy: What do you see as the long-term opportunities and benefits of this new era in biomedical imaging?
Zerhouni: Well, to me the new era is because we are in need of understanding at all scales, from angstrom, you know at the molecular level, to atoms, to molecules, to cells, to tissues, exactly how the complex biological interactions that make health or disease really work. And, imaging is fundamentally a tool to extract biological information or do something about that at all scales. So, whether it be, you know, electron microscopy or CAT scanning or mouse imaging or human imaging, all of that has one fundamental common thread, and that is that now biologists know that to understand biology you really need to know what happens inside too, in vivo, and hopefully without you destroying the system, but by understanding how it really works.
Balintfy: How do you think the NIH is prepared to take advantage of this new biomedical imaging era?
Zerhouni: I think we’ve seen an explosion actually of new ideas, new technologies. For example, one of the fields that has advanced a lot right now is the idea that you could combine a molecule that sends a light, fluorescent molecule, with imaging that doesn’t rely on x-rays, like CAT scanning, or radiation or radio waves, like MRI, but relies on optical imaging. So, now you have the combination of digital optical imaging, like the cameras you have to take pictures, in the laboratory with a probe that is brought into the tissue or the cell to highlight one molecule.
So, one example, NIH and its researchers, Dr. Jennifer Lippincott-Schwartz and her colleagues came up with a technique called photo activated light microscopy. What it is is that she -- Dr. Lippincott-Schwartz and her colleagues can identify a specific molecule. Why? Because they can actually tag the molecule with another molecule that emits light. So as that light comes out, it’s picked up by the microscope. But, it’s controlled. In other words, they can -- they can themselves trigger the light. So that means that you can wait and then when something happens you can trigger the light, say where did it happen in this cell? How did it happen? And that, I think, is going to be an enormous revolution in the way we understand biology in health and disease.
Balintfy: For more information about NIH Director Dr. Elias Zerhouni, visit www.nih.gov /about/director. This interview also appears in the NIH vodcast, “i on NIH” and in the Medline Plus magazine. To see that publication of the National Library of Medicine, visit their website at www.nlm.nih.gov.
Balintfy: And that’s it for this episode of NIH Research Radio. Please join us again on Friday, February 22nd when the next edition of NIH Research Radio will be available for download. I'm your host, Joe Balintfy. Thanks for tuning in.
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.