GLYCINE
Laser technique makes glass fibers In studies of experimental laser techniques for making high-quality glass fiber, a Bell Telephone Laboratories scientist uses a laser beam to melt glass rod so that it can be drawn into a fiber. The carbon dioxide laser, Bell says, is a highly controllable and " c l e a n " source of heat, compared to conven tional heaters that put minute impurities in the glass. Bell foresees the use fulness of glass fibers as a way to transmit light beams carrying telephone messages, data, and computer information.
Aminoacetic Acid N.F. and tech grades FOOD · COSMETICS
factor activity than do those with pri mary tumors. • Observations that recovery of rec ognition factor activity followed, in cer tain cases, initiation of therapy suggest a relationship between tumor growth and development and recognition factor activity. In a symposium on phagocytosis, Dr. Di Luzio described current studies car ried out by his group at Tulane in an attempt to evaluate the influence of recognition factor administration on tumor growth. The studies were con ducted using recognition factor fraction isolated from normal human plasma along with leukemia cells transplanted into rats. Administration of recognition factors with tumor cells, the group found, pro duced about a 90% reduction in tumor growth. By comparison, other human plasma fractions, employed as controls, showed no inhibitory effect on tumor growth and development. This result, Dr. Di Luzio says, denotes the possi bility that isolated recognition factor fraction has a specific anticancer action. To isolate recognition factor fraction from normal human plasma, the re search workers added 20,000 units of heparin per 100 ml. of plasma. The plasma was then maintained at 0° C. for three to six hours for the recognition factor fraction to precipitate. The pre cipitate, collected by centrifugation, was washed with distilled water, lyophilized, and stored at -20° C. The lyophilized fraction, about 1.5 mg. of protein per ml. of plasma, was dissolved in sterile saline to a protein concen tration of 20 mg. per ml. immediately prior to injection. Immunoelectrophoresis, Dr. Di Luzio says, showed that the plasma protein
fraction was heterogeneous. After fur ther purification, it was found that the phagocytic-promoting activity resides in the ^-globulin fraction. In evaluating the ability of recognition factor fraction to modify tumor growth, rats were injected subcutaneously with tumor cells and either the recognition factor fraction, saline solution, or hu man serum albumin. After 10 days, the animals were killed and the tumors ex cised and weighed. In rats receiving tumor cells and saline solution, mean tumor weight on the 10th day was about 10 grams. For those rats receiving recognition factor fraction, there was an 86% decrease in tumor weight. Albumin didn't modify tumor development. To check on whether the inhibitory effect of the recognition factor fraction could be due to direct cytotoxicity, the Tulane group conducted in vitro studies with tumor cells and the fraction. No direct cytotoxicity was found. In an assay of phagocytic-promoting ability of normal human plasma, heparin-precipitate fraction, and super natant, the recognition factor fraction was found to enhance phagocytosis. And studies of the role of recognition factors as chemotactic agents showed that the recognition factor fraction, in addition to enhancing phagocytosis, also has chemotactic properties. All of these findings for recognition factors—ability to enhance macrophage phagocytosis, ability to exert chemo tactic activity, and capability of modify ing tumor growth—further buttress the concept, Dr. Di Luzio says, that recognition factors may be important regulatory factors in macrophagemediated mechanisms in detection or recognition of tumor cells.
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Sept. 17, 1973 C&EN
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