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Hypertension disproportionately affects African Americans, who have a higher incidence of the disease, earlier onset, and more severe symptoms than Caucasians, Hispanics, and Asians. A new study by Columbia researchers finds that signs leading to future hypertension may be detectable even in young, healthy African American males. If more research confirms that the signs are predictors of disease, the researchers say changes in diet and exercise could be effective in slowing the progression of the disease. The study was published May 8 on the Web site of the American Journal of Physiology: Heart and Circulatory Physiology.

The researchers, led by Dr. Ronald De Meersman, adjunct professor of rehabilitation medicine, compared arterial stiffness and nervous system activity in 32 African American males and 29 non-African American males. All volunteers, whose average age was 22, had normal blood pressure and no family history of hypertension.

The African American group, however, had significantly stiffer arteries, and less sensitive baroreceptors that monitor blood pressure – and were less able to reduce blood pressure under stress compared with the non-African American group.

Dr. De Meersman says many reasons probably contribute to the differences between the two groups, including possible genetic differences in receptors that help control arterial stiffness. He is planning to collaborate with geneticists to look for such differences.

"Adopting lifestyle changes at an early age will make a big difference to the vascular system in the long run," Dr. De Meersman says.

The research was supported by the NIH and the VIDDA Foundation, a private foundation.

—Susan Conova

A federally funded multi-center clinical trial that involved Columbia Presbyterian Medical Center showed that lung volume reduction surgery is effective for selected patients with severe emphysema. Emphysema affects about 2 million U.S. smokers and former smokers.

The Centers for Medicare and Medicaid Services, in an unprecedented endeavor, teamed up with the National Institutes of Health to study the surgery – which removes the most damaged parts of the lung – to help the agency decide whether Medicare should cover the procedure. In 1996, the agencies launched the National Emphysema Treatment Trial, a 17-center trial that enrolled 1,218 patients with severe emphysema. All the patients received counseling and exercise training to help manage their condition; about half also received the surgery.

About 80 percent of the 608 people who had the surgery were able to breathe easier and had an overall improved quality of life, says Dr. Mark E. Ginsburg, assistant clinical professor of surgery at P&S and principal investigator for the Columbia portion of the trial.

A subset of that group – patients whose emphysema was most prominent in the upper portion of the lung and who had a low capacity for exercise before the surgery – also lived longer, making them the best candidates for the surgery, Dr. Ginsburg says. Having localized emphysema makes it easier for the surgeon to remove more of the diseased tissue.

Conversely, for patients with diffuse emphysema throughout the lungs and high exercise capacity before surgery, the surgery increased the risk of death. In these patients, it is more difficult for the surgeon to help lung function through surgery because the emphysema damage is widespread.

"This study showed that lung reduction surgery was both safe and effective for properly selected patients," Dr. Ginsburg says. Medicare is expected to come to a decision soon about whether it will provide coverage for the surgery, Dr. Ginsburg says. The findings were published in the May 22 issue of the New England Journal of Medicine.

The study was funded by the NIH, the Centers for Medicare and Medicaid Services, and the Agency for Healthcare Research and Quality.

—Matthew Dougherty

The issue of whether exposure to inorganic mercury from amalgam fillings causes health problems has been the subject of controversy since the introduction of mercury-based dental material in the 1850s. Now, a team of Columbia University public health researchers, dentists, neurologists, and psychologists has found that the amount of inorganic mercury healthy adults are exposed to through dental amalgam fillings is low and does not affect neurological function. The research is published in the May issue of Environmental Health Perspectives.

A CBS "60 Minutes" segment in the early 1990s instigated the latest wave of controversy that has led many people to replace their fillings, but little solid data has been offered on any health effects.

The Columbia study measured mercury exposure, number of fillings, and neuropsychological performance in 550 healthy adults between the ages of 30 and 49. Mercury measured from urine samples reflected long-term exposure to inorganic mercury, the type found in dental amalgam. Organic mercury, the type bound to carbon atoms and frequently found in fish, causes a different set of neurological symptoms.

The researchers found that although mercury exposure rose with the number of fillings, no association was found between mercury level or number of fillings and memory or fine motor performance, says the study's lead author, Dr. Pam Factor-Litvak, associate professor and deputy chairwoman of epidemiology at the Mailman School of Public Health. The average level of mercury measured in the volunteers was 1.7 micrograms per gram of creatine and comes from the vapor given off by the fillings during chewing or the drinking of hot liquids. Previous studies from the 1970s found that dentists, who mixed their own amalgam at that time and thus had higher exposure, averaged between 5 and 8 micrograms, and industrial workers who were exposed to mercury averaged between 50 and 116 micrograms. Based on the current and older studies, the researchers suggest that minor neurological deficits from inorganic mercury begin to be detectable at higher levels than those caused by fillings and thus, healthy adults have no need to have such fillings replaced. The American Dental Association's ethical code prohibits dentists from promoting filling removal as a way to cure disease.

The research was supported by the National Institute of Dental and Craniofacial Research and the National Institute of Environmental Health Sciences.

—Susan Conova

Correction
A headline in the May 26 issue of In Vivo stated that P&S had given a SARS diagnostic test to China. In fact, the test was given by Mailman researchers. We regret the error.


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