Archive for May, 2009

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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STUDY IN NATURE MEDICINE ESTABLISHES MAJOR NEW TREATMENT TARGET IN DISEASED ARTERIES

Sunday, May 10th, 2009

Removing a single protein prevents early damage in blood vessels from triggering a later-stage, frequently lethal complication of atherosclerosis, according to research published online today in the journal Nature Medicine. By eliminating the gene for a signaling protein called cyclophilin A (CypA) from a strain of mice, researchers were able to provide complete protection against abdominal aortic aneurysm (AAA). The aorta is the main artery carrying blood from the heart, and AAA is a progressive outward dilation of the aorta under the stress of blood pressure due to a breakdown in the vessel’s structural integrity. AAA leads to 15,000 deaths a year, mostly in aging men, when aneurysms rupture to spill blood into the abdomen, a fatal event in 90 percent of cases. Adding to the study’s importance, AAA shares vital biochemical pathways with atherosclerosis, the leading cause of heart attack and stroke. Thus, drugs that target CypA could potentially address both AAA and atherosclerosis.When study mice were engineered to remove their CypA gene, none from that group developed AAA in the face of the hypertension and high cholesterol known to accelerate it. In contrast, 78 percent of mice with “normal” amounts of CypA developed AAA under the same conditions, 35 percent with a fatal rupture. The team also found high CypA levels in the rupture-prone vessels of humans with AAA, and that major drugs like statins reduce CypA levels, which may partly explain their benefit.

“It is extremely unusual for the removal of one protein to provide absolute protection, but it makes perfect sense because cyclophilin A promotes three of the most destructive forces in blood vessels - oxidative stress, inflammation and matrix degradation,” said Bradford C. Berk, M.D., Ph.D., professor of Medicine within the Aab Cardiovascular Research Institute at the University of Rochester Medical Center, and senior author of the study. “We are working to design anti-CypA drugs that will diminish the disease processes underlying AAA, atherosclerosis and hypertension.”

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CHEMICAL FOUND IN MEDICAL DEVICES IMPAIRS HEART FUNCTION

Saturday, May 2nd, 2009

Researchers at the Johns Hopkins University School of Medicine have found that a chemical commonly used in the production of such medical plastic devices as intravenous (IV) bags and catheters can impair heart function in rats. Appearing online this week in the American Journal of Physiology, these new findings suggest a possible new reason for some of the common side effects-loss of taste, short term memory loss-of medical procedures that require blood to be circulated through plastic tubing outside the body, such as heart bypass surgery or kidney dialysis. These findings also have strong implications for the future of medical plastics manufacturing. In addition to loss of taste and memory, coronary bypass patients often complain of swelling and fatigue. These side effects usually resolve within a few months after surgery, but they are troubling and sometimes hinder recovery.

His personal experience with coronary bypass surgery propelled his search for a root cause for the loss of taste phenomenon, reports principal investigator Artin Shoukas, Ph.D., professor of biomedical engineering, physiology and anesthesiology and critical care medicine at Johns Hopkins. “I’m a chocoholic, and after my bypass surgery everything tasted awful, and chocolate tasted like charcoal for months.”

Shoukas and Caitlin Thompson-Torgerson, Ph.D., a postdoctoral fellow in anesthesiology and critical care medicine suspected that the trigger for these side effects might be a chemical compound of some kind.

To test their theory, Shoukas and his team of researchers took liquid samples from IV bags and bypass machines before they were used on patients. The team analyzed the fluids in another machine that can identify unknown chemicals and found the liquid to contain a chemical compound called cyclohexanone. The researchers thought that the cyclohexanone in the fluid samples might have leached from the plastic. Although the amount of cyclohexanone leaching from these devices varied greatly, all fluid samples contained at least some detectable level of the chemical.

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