LAB NOTES: Bi-weekly news from the world of science

Britain's first pharmaceutical marijuana farm: Earth's asteroid: and freeze-dried sperm

TREATING TUBERCULOSIS

Deadly drug-resistant strains of tuberculosis have emerged in large part because many patients do not stick with the demanding therapy necessary to cure the disease completely. Patients are supposed to take daily doses of anti-TB medications for two months, followed by another four months of twice-weekly treatments. Because major symptoms of the infection often subside before the course of treatment is complete, many patients simply stop taking their pills because they assume they are cured. But it is this incomplete treatment that allows the tuberculosis organisms to develop resistance to the drugs.

The US Food and Drug Administration has now approved a new medication, rifapentine, that should make adherence easier. TB sufferers need only take rifapentine once a week during the last four months of recovery. The drug, which will be marketed under the name Priftin, is the first anti-TB agent approved in 25 years.

MEDICAL MARIJUANA

A British company has received government approval to begin the world's only marijuana farm devoted to commercial drug development. At a secret location, GW Pharmaceuticals intends to proceed to clinical trials with a smokeless, whole-plant extract, and will also supplying marijuana to other investigators interested in medical research and pharmaceutical development.

The idea of marijuana as an alternative medicine is nothing new: it has been used as a treatment for conditions ranging from the nausea induced by cancer drugs to the fragility of brain cells harmed by strokes. In the United States, oral doses of a synthetic version of marijuana's active ingredient, delta-9-tetrahydrocannabinol (THC), have been available since 1986. But patients have complained that the pill takes too long to relieve nausea - its effect may not be felt for as much as two to four hours, compared with five to 10 minutes for the traditional smoking method. Some proponents of natural marijuana have also argued that the 400 other chemicals present in the plant may interact to produce therapeutic effects beyond those of THC alone. Other scientists maintain that the evidence for synergies between these chemicals is slim.

Interest in whole-plant medicinal marijuana has even stirred in the United States, where research on the drug has been stymied for the last 20 years. One US firm, Unimed Pharmaceuticals, is among several worldwide in various stages of developing nasal sprays, sublingual lozenges, vaporizers, suppositories or skin patches that will deliver THC into the bloodstream quickly. Meanwhile, at the University of California in San Francisco, Robert W Gorier has received FDA approval to perform a clinical trial on an orally-administered whole-plant extract.

KEEPING A SAFE DISTANCE

Most asteroids are far from the sun - beyond the orbit of Mars but inside that of Jupiter. Now, however, astronomers have found an asteroid circling the sun inside Earth's orbit. David Tholen and graduate student Robert Whiteley of the University of Hawaii spotted the object, named 1998 DK36, using a specialised camera on the 88-inch telescope atop Mauna Kea in February. Preliminary calculations show that the asteroid always stays at least 1.3 million kilometers (806,000 miles) away from our planet. This is good news, given that DK36 appears to be 131 feet in diameter. The asteroid that devastated the Tunguska region of Siberia in 1908 was about the same size. The explosion of its impact flattened trees for 50 miles in all directions.

JUST ADD WATER

The wonders of modern science never cease: scientists at the University of Hawaii have managed to produce live mice from dead sperm. They simply added some water to freeze-dried sperm and injected the reconstitued sperm into mouse eggs. The freeze-drying had preserved the genetic information in the sperm well enough for fertilisation to occur and for healthy mice to be born. Freeze-drying is expected to offer an improvement on previous methods of storing genetic information from mice used in research.

All items are adapted from 'Scientific American' Magazine. Visit Scientific American's website at www.sciam.com. Copyright 1998, Scientific American, Inc. All rights reserved.