Proceedings of the National Academy of Sciences. So far, the group has found adenosine receptors in two types of cells, those of the brain and testes, and in two animals, the cow and guinea pig. However, earlier work in their laboratory and several others has found effects of adenosine in many other tissues. Thus, this development of a method to locate and identify adenosine receptor sites is expected to lead to more precise studies of what adenosine does in different cells. In addition to finding adenosine receptors, Snyder and his colleagues have studied possible blocking agents for these receptors. They find two classes of compounds that are excellent antagonists: N 6 -modified nucleosides and methylxanthines. The latter class includes drugs such as caffeine and theophylline, a comTrain derailment near Muldraugh, Ky., pound used to treat asthma. caused vinyl chloride fire "This blocking of adenosine receptors may explain why caffeine is a Muldraugh residents that there is no stimulant," Snyder says. chemical residue that they need clean Although the researchers have off outdoor furnishings, that garden identified two types of adenosine replants probably will be unaffected, ceptors, these are almost certainly not and that garden vegetables may be the only types there are. They find, eaten after the usual washing with for instance, that binding to either of water. The evacuation was ordered these types of receptors does not because of concern that people might block the effect of adenosine on the breathe toxic vinyl chloride vapor. enzyme adenylate cyclase. This U.S. Department of Transportation suggests that there is at least one investigators are now at the scene to more distinct class of adenosine try to determine the cause of the ac- binding sites in cells. And certain cident. D discrepancies in the binding data in guinea pig brains may indicate two subtypes for one of the receptor groups. Adenosine receptor Such variety may be very imporsites identified tant clinically. "Because we have found subtle differences in the two "Adenosine may be like the prosta- types of receptors for adenosine we glandins—a chemical modulator rel- should be able to tailor drugs better evant to the whole body," suggests to prevent heart attacks and treat Solomon H. Snyder, professor of asthma, thus avoiding the serious side neuroscience at Johns Hopkins Uni- effects, such as convulsions, of theversity's school of medicine in Balti- ophylline," Snyder suggests. D more. "It probably regulates neuronal function in the brain, dilates coronary Synthetic fibers blood vessels, constricts the bronchial tree, and inhibits platelet aggregation continue plunge and lipolysis," he says, in addition to inhibiting neuron firing in the brain, The recession is being unmerciful to altering cyclic AMP concentrations in the U.S. fibers industry. the brain, and being a precursor to the Shipments of synthetic fibers have energy storage molecule ATP. been falling all through 1980 to the The latest piece of evidence for the point where total shipments in June multiple and widespread influence of were about 637 million lb, 18.7% this molecule in the body is identifi- below January levels. And shipments cation of at least two types of adeno- are 16.3% below those of June a year sine receptors on cell membranes by ago. The drop has put synthetic fibers Snyder and colleagues Robert F. shipments at their lowest point since Burns of Johns Hopkins and John W. July 1977. Daly of the National Institutes of Noncellulosic yarn and monofilaHealth, Bethesda, Md. Details of ments shipments in June were down their work are expected to be pub- 20.9% from June 1979. Shipments of lished in the September issue of noncellulosic staple and tow fell 8
C&EN Aug. 4, 1980
Drop in fibers shipments continues unabated Millions of lb 800
750
700
650
600
0 Jan
Feb
Mar
Apr
May
Jutte
Source: Textile Organon
12.1%. Those of acetate declined 6.9% and rayon 19.9%. Nylon has really been taking a beating in the past year. In filaments, industrial nylon shipments are down 29.3% from last June, those of lowdenier industrial nylon have dropped 26.7%, carpet filament 27.6%, and textile filament 24.8%. Nylon staple shipments have dropped 44.1%, the largest decline of any of the fiber categories. The only fiber whose shipments have gained in the past year is acrylic staple, rising 8.6%. Industry representatives have no idea when the downturn is going to end, but they hope that some improvement will be seen in August. June and July are the normal seasonal lows for fiber shipments, and producers are hoping that the cyclical low is occurring at the same time. One good sign that producers see is a drop in inventories. June inventories of all fibers dropped 4.5% from May levels. Stocks of all noncellulosics equal about five weeks' shipments at current levels. However, it must be remembered that those shipment levels are very depressed. Thus, a turnaround in demand might send prices up again quickly. Further, industry spokesmen say that price-cutting on most fibers is over, and actually has been for some time. Demand had become so bad that instead of cutting prices, producers were closing plants. There is actually some good news on the price front. Du Pont and Celanese have announced that they are raising prices on polyester textile filament 5 to 9%, effective in September. Others in the industry, however, wonder if the two companies may be premature and thus may wait and see if the price holds. D
