Endangered Creatures Could
Save Us - If We Save Them
By Maggie Fox
Health and Science Correspondent

NEW YORK (Reuters) - When bears hibernate, levels of sugar and fat in their blood are similar to those in humans with diabetes, yet they burn 4,000 calories a day -- as much as a human athlete. Hibernating bears stop eating, drinking and eliminating waste but they continue to build bone and grow lean muscle mass. Females give birth to and nurse cubs and, contrary to popular belief, bears are not even hungry when they emerge after months of slumber. Dr. Ralph Nelson of the University of Illinois thinks his studies of bear metabolism can offer new therapies for human disease from diabetes to obesity and ways for astronauts to deal with long stints cooped up in spacecraft. ``The circumstances of denning should produce early death,'' he told a recent seminar on biodiversity and human health sponsored by the American Museum of Natural History. ``But the bear survives over winter by producing substances that, when developed as drugs, should treat serious human disorders of osteoporosis, kidney failure, obesity, diabetes and anxiety.'' Nelson said the bear is just one example of how the natural environment offers valuable resources for human health. Yet bears are endangered. Shot as nuisances in the United States and Canada, caged in Asia, those that do not fall foul of tourists often fall prey to the traditional medicine trade. The astonishing metabolic qualities of bears did not go unnoticed by the Chinese, who use them to cure a range of disorders including gallstones. ``Bear gallbladders are worth 18 times their weight in gold,'' Dr. Eric Chivian, director of the Center for Global Health at Harvard, told the seminar.
Bears are not the only natural resource threatened by destruction just as scientists start to realize their potential. Drug companies that are actively combing forests and deserts for plants and animals that might offer leads for developing exciting new drugs are painfully aware that this potentially lucrative resource is disappearing virtually before their eyes -- burned for fuel, cleared for farms or developed into cities, towns and even golf courses. The World Conservation Union said in a report last month that more than one-tenth of all the world's plant species were headed toward extinction. A survey this month by the American Museum of Natural History found that 70 percent of biologists polled believe the world is in the midst of a mass extinction of plants and animals and that this loss will pose ``a major threat'' to human existence in the next century. ``It's important to do as much as we can, as soon as we can, to preserve global biodiversity. Nearly all antibiotics have been based on natural products,'' Dennis Schmatz, who heads animal health research at the Merck company, told the seminar. Aware of this, the pharmaceuticals firm has agreements with countries such as Costa Rica that still have virgin forest. Schmatz described one promising product brought back by a team who literally sampled every plant they encountered but found no indication of any potential products. Back in the lab, however, a twig yielded up a fungus that produced a chemical called apicidin, known experimentally as L-755,875, which in test tubes kills cryptosporidium parasites that cause diarrhea and Plasmodium falciparum, which causes malaria. Injected into mice, apicidin can protect them from malaria, something that excited the Merck researchers. ``Whether we get a drug out of it remains a question,'' Schmatz cautioned.
CONE SNAILS LEAD TO PAIN KILLER Meanwhile, California-based Neurex took an interest in cone snails, beautiful creatures collected for their shells in the Philippines and elsewhere. Their beauty comes at a price -- the snails are armed with tiny harpoons connected to poison sacs that can stun and paralyze a fish in milliseconds. Each cone snail secretes dozens of different toxins, which scientists have been analyzing. One blocks calcium channels -- chemical doorways that are important to communication between cells, and Neurex found it can specifically block the kind of pain signals found in chronic, untreatable pain, such as that suffered by cancer patients. They created a synthetic version now named ziconotide. ``In the spinal cord, it blocks synaptic transmissions only between pain-sensing and pain-transmitter nerve cells,'' George Miljanich, senior director of biochemistry at Neurex, said. He said ziconotide is 1,000 times stronger than morphine but does not have the undesirable side effects such as growing tolerance. The effects of morphine start wearing off after about a week and patients need more and more to get the same effect, but with ziconotide, ``the same dose works a year later,'' Miljanich said. Neurex has completed Phase III clinical trials, which show the drug is safe and works. They are now preparing to ask the U.S. Food and Drug Administration (FDA) to license it.
Miljanich hopes other creatures might offer more such drugs. But he, too, is aware that time is running out. ``From which coral reef will come the next cone snail that will treat Parkinson's, or Alzheimer's?'' he asked. ``Are we willing to lose that coral reef?'' Some experts think coral reefs offer a wealth of medicinal miracles, if people take the time to go and find them. ``This could well develop into the major source for new drugs,'' said William Fenical of the Scripps Institute of Oceanography. ``The potential here is enormous. Microscopic organisms alone, there are billions of them in the ocean,'' Fenical, thedirector of the institute's Center for Marine Biotechnology and Biomedicine in San Diego, said. Crowded into the busy underwater city that is a coral reef, many of these organisms have developed chemical offenses and defenses that could translate into important human drugs. One strange, bacteria-like organism found three miles below the surface, where water pressure is 4,000 times air pressure at sea level, produced a protein called macrolactin that, in test tubes, worked against HIV and colon tumors. The organism is so mysterious it defies classification. ``I sent this to five different people who are experts in bacterial taxonomy. They sent it back and said 'good luck,''' said Fenical, who calls the find C-237. The experts have precious little to work with. The sample was small, and unfortunately, Fenical's group can get no more of the protein. ``The organism underwent a mutation and doesn't make the compound any more,'' he told Reuters. And something discovered by accident three miles down is not easy to come by. ''We just haven't run across it again.'' Fenical becomes angry at the thought that such potential miracles could be wiped out by something as carelessly ordinary as pollution. ``To consider that the first site to dump our sewage is the ocean is a frightening prospect to me,'' he said.

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