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Research roundup

22 October 2003

Dangerous herbal product readily available online, scientist warns
A Chinese herbal product known to cause kidney failure and cancer and banned for importation two years ago by the U.S. Food & Drug Administration (FDA) is readily available online, underlining the need for FDA policies regulating the sale of dangerous herbals through the Web, according to Berkeley researcher Lois Swirsky Gold.

In a letter in the Oct. 16 issue of The New England Journal of Medicine, Gold — who directs the Carcinogenic Potency Project at UC Berkeley and Lawrence Berkeley National Laboratory — reports that herbal products containing aristolochic acid can be easily purchased through the Internet, despite 105 documented cases of rapid kidney failure due to use in a Belgian clinic of a diet supplement containing the herbal extract. Half of the 39 women who had their kidneys removed after taking the supplement were found to have cancer of the urinary tract, the letter notes. Kidney failure associated with aristolochic acid has been seen in eight other countries, and urothelial cancer has been seen in two other countries, Gold said.

Many names are used for such products, including fang ji (Aristolochia fangchi) and wild ginger (Asarum canadense). The herbal products, which include those marketed as “Cramp Relief,” “Cold Away,” “Mother Earth’s Cough Syrup,” “Old Indian Herbal Syrup” and “PMS-Ease,” are recommended on the Web for gastrointestinal symptoms, weight loss, cough, immune stimulation, menstrual cramps, and other conditions. A list of products is available at potency.berkeley.edu.

“Aristolochia and aristolochic acid are known human and rat carcinogens,” Gold said in an interview. “These products should not be available.”

Gold alerted the FDA in March to the easy availability of these herbal supplements, after finding on the Web 19 products known to contain aristolochic acid and 95 suspected to contain the chemical. In Chinese herbal medicine, she said, herbs are often substituted for one another, so purchasers can never be certain what the product contains.

“The availability of aristolochic- acid-containing products on the Web two years after an FDA alert was issued reveals a serious flaw in the safety protection afforded the public,” she wrote with co-author Thomas Slone in the NEJM letter. They noted that aristolochic acid “is among the most potent two percent of the carcinogens in our Carcinogenic Potency Database.” The database, which analyzes long-term cancer studies performed in animals, shows that aristolochic acid causes cancer in rats and mice. It also damages rabbit kidneys in the same way that aristolochic-acid-containing supplements damage human kidneys.

In the March 2, 2003, letter to the FDA, Gold and Slone noted that herbal medications containing Aristolochia species were banned in Germany 20 years ago, and they are currently banned in a number of other countries. Under the Dietary Supplement Health Education Act of 1994, however, herbal products do not require FDA approval before marketing.

“There is a common misconception that natural is good, and that, if it has been part of cultures for many centuries, it must be fine,” Gold said. Based on her work with carcinogens, however, she finds that natural chemicals are just as likely to cause cancer as man-made chemicals.
— Robert Sanders

How a sniff, and a smell, affect the brain’s perception of odor
Imagine the smell of coffee in the morning. Did you close your eyes and inhale deeply through your nose? Campus neuroscientists have found that most people do, and that, in fact, this act of sniffing plays a vital role in the brain’s perception of odor.

In the Oct. 19 online issue of Nature: Neuroscience, the researchers report that the sniff people take when trying to imagine an odor closely resembles the one they would have taken if the odor were really there. For example, when imagining the smell of bus fumes, people take a timid sniff, but when imagining the smell of a rose, they take a deep sniff. If prevented from sniffing, the vividness of the image is significantly reduced. From these findings, the scientists conclude that the brain recreates the components of real sensation, such as sniffing, in order to create mental images.

This research “teaches us how the primary olfactory cortex works,” said researcher Moustafa Bensafi. “It has long been known that the act of sniffing, without any odor present, induces neural activity in the primary olfactory cortex, the region of the brain involved in odor perception.” The results suggest that this sniff-induced neural activity is a fundamental component of the olfactory perception, a part of the brain’s representation of smell, the researchers assert.

“As far as the brain is concerned,” Bensafi said, “a sniff and a smell are equally important components in the perception of odor.”

The research was conducted by Bensafi, a postdoctoral research fellow, and Assistant Professor Noam Sobel, both of the campus’s Helen Wills Neuroscience Institute and the psychology department.

Bensafi and collaborators in the Sobel lab, together with a visiting researcher, first studied how 30 Berkeley undergraduates reacted to visual messages. They found that participants spontaneously generated a pronounced sniff when trying to imagine a smell, but not when trying to imagine a sound or sight. And, their sniffs were more vigorous when imagining pleasant versus unpleasant odors.

Findings from these experiments, Sobel said, quantify “what seems obvious, but was never before measured or validated” and point to “a fundamental concept in how the brain may create internal representations of external events.”

They also suggest, he said, “that one strategy used by the brain in this task is to ‘recreate’ or ‘play back’ sensory-motor events, such as sniffing or eye movements, that would normally occur in perception. To perceive an odor we normally sniff, and to help us imagine an odor, or mentally recreate it, we similarly sniff.”
— Carol Hyman