Posts Tagged ‘M.D.’

WHAT MAKES FRUCTOSE FATTENING? OHSU RESEARCHERS FIND ANSWERS IN THE BRAIN

Wednesday, February 9th, 2011

PORTLAND, Ore.

The dietary concerns of too much fructose is well documented. High fructose corn syrup has become the sweetener most commonly added to processed foods. Many dietary experts believe this increase directly correlates to the nation’s growing obesity epidemic. Now, new research at Oregon Health & Science University demonstrates that the brain - which serves as a master control for body weight - reacts differently to fructose compared with another common sweetener, glucose. The research is published in the online edition of the journal Diabetes, Obesity and Metabolism and will appear in the March print edition.

Jonathan Purnell, MD
Jonathan Purnell, MD
Assistant Professor,
of medicine OHSU School
of Medicine
Photo: ohsu.edu

“We know from animal models that the brain responds uniquely to different nutrients and that these responses can determine how much they eat,” said Jonathan Purnell, M.D., an associate professor of medicine (endocrinology, diabetes and clinical nutrition) in the OHSU School of Medicine.

“With newer technologies such as functional MRI, we can examine how brain activity in humans reacts when exposed to, say, carbohydrates or fats. What we’ve found in this case is that the brain’s response to fructose is very different to the response to glucose, which is less likely to promote weight gain.”

Functional MRI allows researchers to watch brain activity in real time. To conduct the research, nine normal weight human study subjects were imaged as they received an infusion of fructose, glucose or a saline solution. When the resulting brain scans from these three groups were compared, the scientists observed distinct differences.

Brain activity in the hypothalamus, one brain area involved in regulating food intake, was not affected by either fructose or glucose. However, activity in the cortical brain control areas showed the opposite response during infusions of the sugars. Activity in these areas was inhibited when fructose was given but activated during glucose infusion.

This is an important finding because these control brain areas included sites that are thought to be important in determining how we respond to food taste, smells, and pictures, which the American public is bombarded with daily.

“This study provides evidence in humans that fructose and glucose elicits opposite responses in the brain. It supports the animal research that shows similar findings and links fructose with obesity,” added Purnell.

The OHSU Advanced Imaging Research Center, the Oregon Clinical and Translational Research Institute at OHSU, the NIH Roadmap for Medical Research, the USDA-ARS Project, the Diabetes Action Research and Education Foundation, and the National Center for Research Resources, a component of the National Institutes of Health, funded this research.

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SELECTED CELLS FROM BLOOD OR BONE MARROW MAY PROVIDE A ROUTE TO HEALING BLOOD VESSELS

Friday, August 13th, 2010

Atlanta, Gorgia - August 13, 2010
Isolating cells from a patient’s blood or bone marrow that nourish blood vessels may be a safer and less arduous route to treatment of cardiovascular disease than obtaining rare stem cells, according to research from Emory University School of Medicine.

Young-sup Yoon, MD, Ph.D
Young-sup Yoon, MD, Ph.D
Emory University
School of Medicine
Photo: stemyoon.org

In recent clinical trials, doctors in several countries have tested the ability of a patient’s bone marrow cells to repair damage, such as heart attacks and peripheral artery disease, created by problems of blood flow.

“The focus has been on stem cells, but it looks like the main beneficial effects come from transplanted cells’ ability to support the growth of nearby blood vessels,” says senior author Young-sup Yoon, MD, PhD, associate professor of medicine (cardiology) at Emory University School of Medicine. “Based on this idea, we wanted to identify a population of cells enriched with the capacity to regenerate blood vessels.”

The blood vessel repairing properties of selected cells from human blood were described in the Aug. 10 issue of the Journal of the American College of Cardiology, with a related paper on cells derived from mouse bone marrow published online July 15 by the journal Circulation Research.

The first author of the JACC paper is postdoctoral fellow Sung-Whan Kim, PhD. The first author of the Circulation Research paper is Hyongbum Kim, MD, PhD, now an assistant professor in Korea.

Yoon’s team focused on the molecule CD31, also known as platelet endothelial cell adhesion molecule-1 or PECAM-1, because of its presence on endothelial cells - the cells that form the inner lining of blood vessels. In experiments with donated blood from human volunteers or mouse bone marrow cells, the researchers showed that cells with CD31 on their surfaces secrete hormones that support the growth of blood vessels.

About a third of the cells in the blood or bone marrow have CD31 on their surfaces, including some differentiated immune cells. In culture, sorted cells displaying CD31 can form tubular structures mimicking the growth of blood vessels in the body.

“We can show that after transplantation, some CD31 positive cells do become endothelial cells, but their main effect is more to support other cells than to become the building blocks,” Yoon says.

The researchers used antibodies against CD31 to sort human blood or mouse bone marrow cells into two groups: cells with CD31 and those without. They then tested these cells’ ability to spur blood vessel regrowth in mice whose hind legs had a blocked blood supply.

In the project described in Circulation Research, after two weeks more than 80 percent of the mouse hind legs transplanted with CD31 positive bone marrow cells survived, while less than 15 percent of the legs transplanted with CD31 negative cells survived. In laser Doppler images, the mice with CD31 positive cells injected into their legs had greatly enhanced blood flow and an increased number of capillaries.

Yoon says harvesting CD31 positive cells may have several advantages compared to previous methods of treating cardiovascular disease. The cells can be prepared without the need to grow them in a dish for several days, and it may not be necessary to take large volumes of blood or bone marrow from the patient - an advantage with respect to safety. In addition, cells from mice used to simulate atherosclerosis (mutant for a gene that helps clear fat from the blood and given a high fat diet) do not seem to lose their repair potential.

“Based on the insights gained from preclinical and clinical studies from several investigators, we view the use of CD31 positive cells as a second generation cardiovascular cell therapy that could be a novel option for the treatment of peripheral artery disease,” Yoon says.

He adds that CD31 positive cells may have potential for treating other conditions, including heart attack, heart failure and diabetic neuropathy, which his team is investigating in animal models.

The research was supported by the National Institutes of Health, the Department of Defense and the Korean Ministry of Education, Science and Technology.

Learn more about Emory’s health sciences: http://emoryhealthblog.com

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NEW METHOD TO GROW ARTERIES COULD LEAD TO “BIOLOGICAL BYPASS” FOR HEART DISEASE

Monday, March 8th, 2010

(Yale University)
A new method of growing arteries could lead to a “biological bypass”-or a non-invasive way to treat coronary artery disease, Yale School of Medicine researchers report with their colleagues in the April issue of Journal of Clinical Investigation.

Michael Simons,MD
Michael Simons,MD -
chief of the Section of
Cardiology at Yale
School of Medicine
photo: yalemedicalgroup.org

Coronary arteries can become blocked with plaque, leading to a decrease in the supply of blood and oxygen to the heart. Over time this blockage can lead to debilitating chest pain or heart attack. Severe blockages in multiple major vessels may require coronary artery bypass graft surgery, a major invasive surgery.

“Successfully growing new arteries could provide a biological option for patients facing bypass surgery,” said lead author of the study Michael Simons, M.D., chief of the Section of Cardiology at Yale School of Medicine.

In the past, researchers used growth factors-proteins that stimulate the growth of cells-to grow new arteries, but this method was unsuccessful. Simons and his team studied mice and zebrafish to see if they could simulate arterial formation by switching on and off two signaling pathways-ERK1/2 and P13K.

“We found that there is a cross-talk between the two signaling pathways. One half of the signaling pathway inhibits the other. When we inhibit this mechanism, we are able to grow arteries,” said Simons. “Instead of using growth factors, we stopped the inhibitor mechanism by using a drug that targets a particular enzyme called P13-kinase inhibitor.”

“Because we’ve located this inhibitory pathway, it opens the possibility of developing a new class of medication to grow new arteries,” Simons added. “The next step is to test this finding in a human clinical trial.”

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UT HOUSTON RESEARCHERS LAUNCH PHASE II TRIAL OF STEM CELLS AND ACUTE HEART ATTACK

Tuesday, December 8th, 2009

HOUSTON - The second phase of a clinical trial testing a new stem cell based therapy on injured heart muscle has been launched by researchers at The University of Texas Medical School at Houston. It is the only study site in the Texas Medical Center.

Dr. Ali Denktas, Patient Melvin Dyess
Patient Melvin Dyess, far right,
participates in phase II of a stem
cell trial at the University of
Texas Medical School at Houston,
where Dr. Ali Denktas, center,
is the lead investigator.
photo: Deborah Mann Lake

Results from Phase I of the trial are published in today’s issue of the Journal of the American College of Cardiology. Researchers reported that patients were treated safely with intravenous adult human mesenchymal stem cells (Prochymal) after a heart attack. In addition, they had fewer arrhythmias, improved heart and lung function, and improvement in overall condition.

“We are able to use a stem cell product that is on the shelf without prior preparation of anything from the patient, and this product appears to be able to help the heart muscle recover after a heart attack,” said Ali E. Denktas, M.D., the trial’s Houston site principal investigator and assistant professor of cardiology at the UT Medical School at Houston. “This means patients have the potential to recover quicker with less risk of an immediate secondary attack.”

In many cell based therapies, doctors harvest the patient’s own cells, process them and then return them to the patient. Prochymal, developed by Osiris Therapeutics, Inc., contains adult mesenchymal stem cells from healthy donors. The cells can be stored at an emergency center until needed. For purposes of the Phase II study, Prochymal must be administered within seven days of a heart attack.

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GREEN TEA SHOWS PROMISE AS CHEMOPREVENTION AGENT FOR ORAL CANCER

Thursday, November 5th, 2009

HOUSTON - Green tea extract has shown promise as cancer prevention agent for oral cancer in patients with a premalignant condition known as oral leukoplakia, according to researchers at The University of Texas M. D. Anderson Cancer Center. The study, published online in Cancer Prevention Research, is the first to examine green tea as a chemopreventative agent in this high risk patient population. The researchers found that more than half of the oral leukoplakia patients who took the extract had a clinical response.

Long investigated in laboratory, epidemiological and clinical settings for several cancer types, green tea is rich in polyphenols, which have been known to inhibit carcinogenesis in preclinical models. Still, clinical results have been mixed.

“While still very early, and not definitive proof that green tea is an effective preventive agent, these results certainly encourage more study for patients at highest risk for oral cancer,” said Vassiliki Papadimitrakopoulou, M.D., professor in M. D. Anderson’s Department of Thoracic/Head and Neck Medical Oncology, and the study’s senior author. “The extract’s lack of toxicity is attractive - in prevention trials, it’s very important to remember that these are otherwise healthy individuals and we need to ensure that agents studied produce no harm.”

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REDUCTION IN GLYCOTOXINS FROM HEAT PROCESSING OF FOODS REDUCES RISK OF CHRONIC DISEASE

Wednesday, November 4th, 2009

Researchers from Mount Sinai School of Medicine report that cutting back on the consumption of processed and fried foods, which are high in toxins called Advanced Glycation End products (AGEs), can reduce inflammation and actually help restore the body’s natural defenses regardless of age or health status. These benefits are present even without changing caloric or nutrient intake. The findings, published in the October/November issue of the Journal of Clinical Endocrinology and Metabolism, provide a simple dietary intervention that could result in weight loss and have significant impact on several epidemic diseases, including diabetes, heart disease, and kidney disease.

The findings are the result of a clinical study involving over 350 people which was conducted in collaboration with, and with support from, the National Institute on Aging (NIA). The study builds on earlier research conducted in animal models that demonstrated the effective prevention of these diseases and even the extension of lifespan by consuming a reduced AGE diet.

“What is noteworthy about our findings is that reduced AGE consumption proved to be effective in all study participants, including healthy persons and persons who have a chronic condition such as kidney disease,” said the study’s lead author Helen Vlassara, MD, Professor and Director of the Division of Experimental Diabetes and Aging at Mount Sinai School of Medicine.

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PIECE FROM CHILDHOOD VIRUS MAY SAVE TRAUMA LIVES

Monday, September 7th, 2009

Research presented Sept. 6 at European complement conference

A harmless shard from the shell of a common childhood virus may halt a biological process that kills a significant percentage of battlefield casualties, heart attack victims and oxygen deprived newborns, according to research presented Sunday, September 6, 2009, at the 12th European meeting on complement in human disease in Budapest, Hungary.

Introducing the virus’s shell in vitro shuts down what is known as the complement response, a primordial part of the immune system that attacks and destroys the organs and vascular lining of people who have been deprived of oxygen for prolonged periods, according to researchers at Children’s Hospital of The King’s Daughters (CHKD) and Eastern Virginia Medical School (EVMS), in Norfolk, Va.

The complement response kicks in after the victim has been revived, in what is known as a reperfusion injury. It does its work slowly but unrelentingly, killing soldiers, infants or heart attack victims over the course of days.

“To find a way to manipulate the complement system pharmacologically has been like a search for the Holy Grail,” said one of the lead researchers, Dr. Kenji Cunnion, an infectious disease physician at CHKD and an associate professor of pediatrics at EVMS.

While Cunnion and Neel Krishna, Ph.D., a pediatric virologist at CHKD and assistant professor of microbiology at EVMS, focus on pediatric research, they see clear military applications.

“The complement reaction is one of the major causes of death of the battlefield,” said Krishna. “By the time you get a victim to the hospital, it may be too late.”

Dr. L.D. Britt, M.D., MPH, Brickhouse professor and chairman of surgery at EVMS, agrees.

“Hemorrhagic shock is the leading cause of death in combat trauma and reperfusion injury plays a significant role both in increased mortality and increased brain damage,” said Britt.

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GREEN TEA EXTRACT SHOWS PROMISE IN LEUKEMIA TRIALS

Tuesday, May 26th, 2009

ROCHESTER, Minn. - Mayo Clinic researchers are reporting positive results in early leukemia clinical trials using the chemical epigallocatechin gallate (EGCG), an active ingredient in green tea. The trial determined that patients with chronic lymphocytic leukemia (CLL) can tolerate the chemical fairly well when high doses are administered in capsule form and that lymphocyte count was reduced in one third of participants. The findings appear today online in the Journal of Clinical Oncology. “We found not only that patients tolerated the green tea extract at very high doses, but that many of them saw regression to some degree of their chronic lymphocytic leukemia,” says Tait Shanafelt, M.D., Mayo Clinic hematologist and lead author of the study. “The majority of individuals who entered the study with enlarged lymph nodes saw a 50 percent or greater decline in their lymph node size.”

CLL is the most common subtype of leukemia in the United States. Currently it has no cure. Blood tests have enabled early diagnosis in many instances; however, treatment consists of watchful waiting until the disease progresses. Statistics show that about half of patients with early stage diseases have an aggressive form of CLL that leads to early death. Researchers hope that EGCG can stabilize CLL for early stage patients or perhaps improve the effectiveness of treatment when combined with other therapies.

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OMEGA-3 FATTY ACIDS PREVENT MEDICAL COMPLICATIONS OF OBESITY

Friday, February 13th, 2009

New article in the FASEB Journal shows how omega-3 fatty acids protect against liver damage and insulin resistance

According to a recent study published online in The FASEB Journal, diets rich in omega-3 fatty acids protect the liver from damage caused by obesity and the insulin resistance it provokes. This research should give doctors and nutritionists valuable information when recommending and formulating weight-loss diets and help explain why some obese patients are more likely to suffer some complications associated with obesity. Omega-3 fatty acids can be found in canola oil and fish.

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STUDY RAISES QUESTIONS ABOUT PLASTICS CHEMICAL

Wednesday, January 28th, 2009

A University of Rochester Medical Center study challenges common assumptions about the chemical bisphenol A (BPA), by showing that in some people, surprisingly high levels remain in the body even after fasting for as long as 24 hours. The finding suggests that BPA exposure may come from non-food sources, or that BPA is not rapidly metabolized, or both. The journal Environmental Health Perspectives published the research online January 28, 2009.

Controversy around BPA is mounting. In December the U.S. Food and Drug Administration agreed to reconsider the health risks of the chemical, which is used to make plastic baby bottles, water bottles and many other consumer products. Scientific studies suggest that BPA may harm the brain and prostate glands in developing fetuses and infants; adults with higher BPA levels in their urine were linked to higher risks for heart disease and diabetes, according to a study published last September in the Journal of the American Medical Association.

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