now being made available." Nei ther does the field of education hold out much promise of being able to take up the slack because of the steady decline in the numbers of school-age children, he says. But in California, where employ ment cutbacks among skilled pro fessionals have been particularly severe because of the heavy con centration of aerospace companies there, a more hopeful outlook is developing. For instance, Dr. Chauncy Starr, dean of engineering and applied sciences at the Univer sity of California, Los Angeles, views the current unemployment condition as temporary, maintain ing that the situation will reverse itself soon. He bases his belief on the growth in national demand for technologically educated individu als which, in turn, is keyed to the technological development of soci ety. Indeed, Dr. Starr says that a shortage of engineers and scien tists could develop within seven years. Across town, Dr. John Marshall, director of the University of South ern California's industrial associ ates program, shares Dr. Starr's opinion. He foresees, for example, an expanding demand for people with competence in computer, bio medical, and ocean engineering. And he views USC's chemical and petroleum engineering division's enlarging its teaching staff as indic ative that the need for chemical engineers is on the upswing. He admits, however, that unemployed professionals who are in their for ties or older are finding it difficult to make a transition into areas of expertise different from the ones they have been trained in.
more, Md. The symposium was sponsored by Miles Laboratories. The results on repair in human and cattle cells stem from Dr. Clea ver's research (supported by the U.S. Atomic Energy Commission) on xeroderma pigmentosum (XP), a hereditary human disease that can produce skin cancer, and his re search on cancer eye, an inherited disease that appears with varying frequencies in inbred strains of cat tle. XP cells are defective in re pairing ultraviolet radiation dam age to deoxyribonucleic acid (DNA), but cells from cattle with cancer eye have no detectable de fect in DNA repair. At present only the work with XP has given evi dence for the functional significance of one pathway for DNA repair in animal cells, Dr. Cleaver says. XP appears to be the human analog of the E. coli UVR- HCRr bacterial mutants, he says. XP cells are much more sensi tive to UV radiation than are nor mal cells, Dr. Cleaver says. The sensitivity of cattle cells, however, is independent of the incidence of cancer, he finds. Thus, cancer eye is clearly not analogous to XP. When human cells are allowed to grow after UV irradiation, normal cells excise some of the pyrimidine dimers (50 to 75% at low doses) from their DNA, whereas XP cells
apparently do not, Dr. Cleaver says. Cattle cells, after UV irradiation, similarly excise pyrimidine dimers from DNA. Dr. Cleaver's research shows that XP cells in vitro are sensitive to kill ing by UV light and have reduced ability to support the reproduction of UV-inactivated viruses. And XP cells insert fewer bases into DNA during repair of UV damage than do normal cells. The evidence indicates that an enzyme involved in excision is de fective in XP cells, Dr. Cleaver says. At present, however, there is no di rect evidence of the nature of the defective enzyme. Future work on isolation of enzymes involved with excision repair in mammalian cells may clarify this problem. BIOCHEMISTRY:
Imino acid intermediates With the trapping of imino acid in termediates in amino acid oxidase reactions comes confirmation of an essential mechanism of protein me tabolism. The new evidence was found by Dr. Daniel Wellner of Cor nell University medical college, New York City, who in 1961, with Dr. Al ton Meister, proposed the most widely accepted scheme to explain observations of oxidation of amino acids to α-keto acids. Additional
MEDICINE:
Mechanism of cell repair Concern about environmental radi ation hazards and the cancer prob lem has spurred scientists to ac quire more information on repair processes in damaged cells. Rep resentative of the resultant under standing of molecular repair proc esses are findings that mammalian cells, particularly those in humans and cattle, have a repair pathway similar to excision repair in bac teria. Dr. James E. Cleaver of the University of California, San Fran cisco, explained these findings at the 5th International Symposium on Molecular Biology held at Johns Hopkins medical school in Balti
Fingernail analysis spots cystic fibrosis Dr. Richard E. Wainerdi (left) and Dr. Lloyd E. Fite, at Texas A&M's activation analysis research laboratory, College Station, analyze infants' fingernails for cop per content to detect cystic fibrosis. The disease occurs at a rate of one in 2500 infants. It is disabling and eventually fatal, but early detection and treatment can add many years to an infant's life. Fingernails of normal newborns contain 2 to 30 p.p.m. of copper; those of infants with cystic fibrosis, 50 to 200 p.p.m., Dr. Wainerdi says. Coupling neutron activation analysis with a computer, the Texas group analyzes fingernail clippings from cystic fibrosis centers all over the U.S. The project is headed by Dr. Guyon Harrison of Baylor College of Medicine, Houston, and may lead to mass screening of all infants.
JUNE 14, 1971 C&EN
11
Chemical world This Week dividends from knowledge of imino als for specific medical uses; thus, acid intermediates may come from most biomedical plastics are fallout conversion of synthetic racemic from research aimed at nonmedical amino acids to optically active markets. forms [Proc. Nat. Acad. Sci., U.S., U.S. sales of fabricated biomedi68, 987 (1971)]. cal plastics will increase from $150 Working with Edmund W. Haf- million in 1971 to $300 million in ner in the project supported by the 1976, Kline & Co. says. The firm U.S. Public Health Service, Dr. Well- estimates that 1971 sales will inner adds sodium borohydride to clude dentures and related prodreaction mixtures of D-amino acid ucts, $40 million; contact lenses, oxidase and such amino acids as D- $30 million; catheters, $20 million; alanine, D-phenylalanine, D-methio- blood collecting systems, $10 milnine, and D-leucine; he detects lion; medical grades of tubing and about 5% conversion to L-amino sheeting, $5 million; and cardiovasacid. He theorizes that boro- cular prosthetics, orthotics, encaphydride reduces imino groups, be- sulants, dialysis membranes, excause conversion to opposite enan- ternal prosthetics, and other prodtiomorphs indicates a symmetrical ucts, $45 million. intermediate. In other experiPlastics are making inroads into ments, he verifies that borohydride products traditionally made from cannot racemize amino acids or in- other materials—for example, hibit amino acid oxidases. Foley catheters, a $15 million marExperiments with 14C-D-alanine ket for natural rubber. Other bioshow that reduction of imino acids medical markets being invaded by to amino acids is about 36 times plastics include sutures, a $70 milmore rapid than hydrolysis to py- lion market for catgut and silk, and ruvate. Consequently, he reasons intravenous solution containers, an that imino acids do not build up to $8 million market for glass. appreciable concentrations while In 1971 about 15 million pounds the enzyme is working. of plastic resins valued at $7 million Whereas both D- and L-amino acid will be used in biomedical products, oxidases are specific to D- or L- Kline & Co. says. Consumption will amino acids, each enzyme can ac- likely grow 15% per year during cept about 10 different amino acids. the next five years to 30 million Therefore, Dr. Wellner sees the en- pounds valued at $14 million in zyme-cum-borohydride system as a 1976. Although biomedical polymeans to convert racemic mixtures mers are unlikely to become largeto single enantiomorphs. D-Amino tonnage items, purity and quality reacid oxidase will leave L-amino acids quirements are so critical that these unchanged, while some D-amino resins command higher prices than acid is converted to the L form those for industrial uses. when borohydride reduces the inKline & Co.'s estimates of U.S. termediate imino acid. Thus a DL consumption of resins in biomedimixture is enriched in L isomer. cal applications this year include 10 The Cornell scientists have verified million pounds of polyvinyl chlothis possibility with alanine, phenyl- ride, 1.5 million pounds of polyalanine, and methionine. They see methyl methacrylates, and 500,000 use for the method in converting pounds of silicones. Accounting racemic synthetic DL-3,4-dihydroxy- for about 3 million pounds is a vaphenylalanine to L-dopa, although riety of other polymers, including they have not yet attempted that polyesters, polycarbonates, polyurereaction. thanes, fluoropolymers, irans-polyisoprene, hydroxyethyl methacrylate, polyglycolic acid, polyethylene, PLASTICS: and polypropylene. Biomedical uses to double PVC is used extensively for blood Use of plastics in biomedical appli- bags, tubing, and intravenous socations continues to grow at a fast lution containers. Poly methyl clip. U.S. consumption of plastics methacrylates are used primarily for use in and on the human body in dentures, contact lenses, and and in contact with human blood bone substitutes. Silicones find apwill double in the next five years, plications in cosmetic surgery, tubaccording to advance estimates ing, catheters, cannula, and encapfrom a survey currently under way sulants. Polyesters are used in arby C. H. Kline & Co., Fairfield, N.J. tificial limbs and vascular prostheMost plastics producers seem re- ses; and polycarbonates in blood luctant to investigate new materi- oxygenators and dentures. 12
C&EN JUNE 14, 1971
I MAGNESIUM:
Dow moves lab to Battelle Battelle Memorial Institute will establish an international magnesium research center at its Columbus, Ohio, laboratories. In effect, Battelle will take over and eventually expand Dow Chemical Co.'s activities in magnesium R&D. Dow will transfer its files on magnesium to Battelle for "a nominal sum" and will place an initial $1 million, fiveyear research contract with the new center. At Battelle's request, Dow is also "encouraging" a few of its key workers to transfer to the new center. Dr. Robert S. Busk, assistant director of research & development at Dow, disclosed the plans at the annual conference of the Magnesium Association, held last week on Mackinac Island, Mich. He explains that Dow had asked Battelle to establish the center, and that Dow's intention was to have a research center dedicated to serving the entire magnesium industry in the areas of physical metallurgy and applications development. Dow views the move as an important stimulant to the continued growth of the magnesium business, Dr. Busk says, adding that, although Dow alone had approached Battelle, the action followed consultations with other companies. The Dow files being transferred to Battelle contain about 14,000 separate reports accumulated over more than 50 years of magnesium research at the company. The files also include indexes listing nearly all pre-1944 scientific publications on magnesium. Battelle's H. Russell Ogden, who will direct the center, says the Dow material will provide the point of departure for a variety of planned R&D programs, to be conducted on a contract basis for producers and users of magnesium. Dow is the pioneer in the largescale extraction of magnesium from brines and from sea water. The firm, a dominant producer, has long been the leader in promoting applications for the metal. Recent ventures by American Magnesium Co. and others have cut into Dow's long-time 90% share of the domestic market; the transfer of Dow's magnesium R&D functions implies that the firm thinks it's time for others to pick up a proporI tional share of the R&D tab.
