Three Mile Island accident, 236 had not been completed by this past Jan uary, he points out. Murphy says that the study, called "Potential Precursors to Severe Core Damage," gives NRC a list of singleevent failures ranked in order of probability of their leading to a core melt. "It will allow the commission to survey the list to make certain that there are no holes in its licens ing process. It becomes one more element in NRC's decision-making process," he says. The current study was undertaken to answer critics of the WASH 1400 report. T h a t widely cited report made an accident risk assessment based on an analysis of one pressur ized water reactor in Virginia. Mur phy says that plant is well designed and "may have been more reliable than the industry average." To assure validity of this most recent assessment, Murphy says the document will be peer reviewed, both for its system engineering assump tions and for its statistics. The Amer ican Statistical Association likely will be involved in the review, Murphy says. D
First synthetic peptide vaccine produced A 20-amino-acid peptide that causes production of antibodies to foot-andmouth disease virus in cattle, guinea pigs, rabbits, and pigs and protects guinea pigs (the only animals tested thus far) against infection by the virus has been synthesized chemically by scientists at the Research Insti tute of Scripps Clinic, La Jolla, Calif., and at the Animal Virus Research Institute, Pirbright, England [Na ture, 298, 30 (1982)]. It is the first synthetic vaccine ever produced. The peptide's activity is remark able because of its size. According to the researchers, the intact footand-mouth virus consists of an RNA molecule with 60 copies of each of four proteins forming the coat around it. Previous research in other labs had shown that only one of the pro teins, which consists of 213 amino acids and is designated VP1, was responsible for the immune response to the virus. However, that protein, when isolated from the virus chemi cally or produced in bacteria via re combinant DNA techniques, elicited little or no response. The effective, synthetic peptide is a copy of a 20-amino-acid segment of a central portion of VP1.
The research effort was carried out with private funding by Fred Brown and a coworker in the U.K. and by Richard A. Lerner and co workers in the U.S. According to Lerner, several different strains of foot-and-mouth disease viruses exist. In these strains, only certain parts of the VP1 protein vary. "Our rea soning was that the virus changes to escape the immune system," Lerner says. In other words, the immune system is driving the variation, and therefore the sites of variation are the ones that are available to anti bodies. Seven sections of VP1 were tested, and the section that works to produce immunity was the one that varied the most. That the peptide functions as a vaccine is i m p o r t a n t . Foot-andmouth disease occurs in every con tinent except North America and Australia. More than 1 billion doses of vaccine produced from inactivated whole virus are administered each year, but such vaccine is unstable and requires refrigeration. Perhaps more important, says Lerner, is that the peptide vaccine forces some reconsideration of how the immune system recognizes for eign material. Previously, most sci entists t h o u g h t t h a t antibodies recognized a protein because of its conformation, which can bring dis tant regions of the protein into close proximity. At least in the case of foot-and-mouth disease virus, he says, that can't be true because the immune system responds better to a small segment of the protein than it does to the intact protein. According to Lerner, the research opens up the possibility of produc ing antibodies of predetermined specificity. Π
Diamond Shamrock may buy gas retailer Diamond Shamrock has signed a let ter of intent to acquire San Antoniobased Sigmor Corp., a gasoline retailer. The move will bolster Dia mond Shamrock's growing gasoline marketing and refining operations. It also will hasten the company's slow but sure evolution from a chem icals company to a multiresource en ergy company. The total deal could be worth $156 million. Sigmor had-sales of $1.8 billion and net earnings of $31.8 million in fiscal 1981, which ended June 30, 1981. Diamond Shamrock's 1981 sales and operating revenues were
Bricker: diversifying for growth
$3.38 billion, and earnings were $121.3 million. From being primarily a chemical company, Diamond Shamrock has been changing emphasis. Last year, chemicals accounted for 36% of the company's revenues but only 29% of operating profits. T h e company already had an nounced, in 1981, the sale of .some of its chemical operations—for ex ample, a substantial portion of its polyvinyl chloride business to B. F. Goodrich—and a discontinuation of its animal-nutrition businesses. During the past year, Diamond Shamrock has been the rumored tar get of takeover bids, which pushed the stock price up to a high last year of nearly $40 per share before it declined to about $19 last week. Wall Street analysts doubt that the new purchase was designed to prevent a takeover bid. As one ana lyst sees it, the acquisition is, rath er, a continuing drive by Diamond Shamrock to work out of the chemi cals business and become an energy company. When chairman and chief executive officer William H. Bricker took over, Diamond Shamrock was basic inorganic chemicals, says the analyst. "They were mature indus tries, with nowhere to go. Bricker diversified into an area with better growth potential. It's been almost a class-book case of evolution." Bricker himself addressed t h a t topic at a New York City security analysts meeting last week. "Every thing has its time," he said, "and right now, there aren't many chemi cal projects we can be enthusiastic about investing in." D July 12, 1982 C&EN
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