By Lidia Wasowicz
UPI Senior Science Writer
Published 1/22/2002 4:45 AM

GENETIC TIES TO BIG HEARTS

A genetic defect found in some 20 percent of the population might be the reason some people develop a dangerously enlarged heart after intensive exercise or as a side effect of high blood pressure. That word comes from a study published in Circulation: Journal of the American Heart Association. An enlarged heart, also called left ventricular hypertrophy, can lead to congestive heart failure, a condition that affects about 4.8 million Americans. LVH may also cause sudden cardiac death. Scientists say 36 percent of young athletes who die suddenly have probable or confirmed LVH. David Flavell of University College London Medical School led a study to find out why some individuals who weight train or who have high blood pressure are more likely to develop LVH than others. "We know there are physical causes for LVH. It is normal for the heart to grow in response to exercise, but we wanted to find out the genetic components contributing to the abnormal growth that leads to LVH," he said. Scientists found in their mouse studies that a gene called peroxisome proliferator activated receptor alpha was likely to blame for enlarged hearts.

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TAILOR-MADE LIMITS ON TUMORS

Sugar jackets "worn" by cancer cells can be tailored to stop tumors dead in their tracks, researchers found. The work, which could lead to drugs that attack cancer cells in a specific manner, is reported in the journal Proceedings of the National Academy of Sciences. Complex sugars and proteins are key components of a web of material that surrounds every cell. This extracellular matrix is key to cell function. It orchestrates how signals from outside the cell are processed and perceived. Growing understanding of the web proteins and their roles has led to such new drugs as the anti-cancer endostatin, but insights into the sugars -- which are more complex and harder to study -- have not been as forthcoming. But now researchers at the Massachusetts Institute of Technology have developed new tools to delve into the sugars' secrets. Led by Ram Sasisekharan, an MIT team used these tools to probe the relationship between changes in tumor cells' sugar jackets and cancer. "We were fascinated by the discovery that the tumor cell's sugar coat contains sugar sequences that can both promote and inhibit growth," Sasisekharan said. "Tumors might be kept in check by the body's production of specific enzymes that in turn release sugar fragments that keep tumor cells dormant. Or, perhaps in response to pathophysiological changes, a tumor cell releases different enzymes that enable the tumor to grow more rapidly."

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TESTOSTERONE AND ALZHEIMER'S

The male hormone testosterone, alone or with estrogen, can prevents one of a key abnormality characteristic of Alzheimer's disease, a study suggests. Neurofibrillary tangles, a hallmark of a brain affected by Alzheimer's, are bundles of aberrant filaments made up mostly of a brain protein called tau. Tau is transformed by a chemical reaction called hyperphosphorylation. Exposing rats to excessive heat over-activates three enzymes linked to this process. A study at the University of Texas Medical School at Houston now shows that testosterone, with or without estrogen, prevents the unwanted tau transformation. Estrogen has been widely studied for its potential benefits in delaying or preventing Alzheimer's, but not so testosterone. The new study indicates that giving testosterone to aging men or women in combination with estrogen may help delay, prevent or treat Alzheimer's, doctors said.

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NEW TARGEST FOR DRUGS AGAINST CANCER

Polysaccharides are complex sugar molecules found on the surface of cells. These molecules may serve as targets for anti-cancer drugs, researchers say. Specific features of the sugar coating on tumor cells may tell how far along and how aggressively a cancer has progressed. Whether these changes are a cause or consequence of tumor progression has not been known. A new study by Massachusetts Institute of Technology scientists shows alterations in the polysaccharides can spark and suppress the growth and spread of a tumor. The authors identified regions of the sugar coating on melanoma cells that affect tumor development. The mouse studies showed that different polysaccharide fragments either activate or inhibit the activity of specific molecules involved in tumor progression. The release of the fragments that inhibit not only hinders the proliferation and survival of tumor cells but also prevents the formation of blood vessels to feed the tumor. So the sugar coating on tumor cells, which varies according to tissue type, may provide a tissue-specific target for new anti-cancer therapies, the authors concluded.

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(EDITORS: For more information about HEARTS, call 214-706-1396; about TUMORS, call 617-258-5402; about ALZHEIMERS, call 713-500-3304; about CANCER, call 617-258-9494.)