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Top 10 announced in Science Talent Search Alan John Hu~ mixed mathematics withh computer science and' came up with the winning cornbination in the 44th annual Westinghouse Science Talent Search this week. Hu, of La Jolla. Calif:, took first place and a $12.000 scholarship. First in his class atLa Jolla HS., Hu topped the select group of 40 seniors from 13' states and Puerto Rico by devising a method to speed'the.lo- cation of:1information in a specific com- puter file. Hus system minimizes the time spent~ making, comparisons in a file and moving tape: He plans to study mathemat- ics and!computer science at Stanford Uni- versity. Anna Asher Penn oLChicago, a student at the University of Chicago llaboratory Schools HS.. was awarded second place and a $1101000 scholarship. For her project; she produced DNA clones ofone segment of a bacterial virus that can i be used to study how viruses: such as influenza: re- Cardinal Spellman ~ HS., Audrey Zelicof of' New Y'ork City, astudent at Stuyvesant HS:, and Allan Moises Goldstein of M'yncote; Pa.. a student at Cheltenham HS. Two alternates were also named in case any of the top 10 winners is not able toac- cept a scholarship: They are Jonathan Michael Passner of East Brunswick. NJ., a student at the Jewish Educational Center, and~Mark Raboin Swain of Manaasas, Va., a student' at Stonewalli Jackson HS. Along with the remaining 28 national winners; they will receive cash awards of, 55000 each:. The competition, with a total of S'89500 in Westinghouse Scienceseholarships and awards, is conducted i by Science Service. Inc. 0 produce in host cells. Penn is continuing research in flatworm regeneration at her high school and plans to study molecular biology at Harvard University. In another, combination of mathematics with computers, Michael Friedman of Brooklyn. N.Y', won third place and a $10.000 scholarship. By running his own number-theoretic formulas through a computer. Friedman demonstrated that an odd perfect number must be at least 10'to the 79th power An odd Iperlect number is one for which the sum of' its factors is twice the original number: No such num- ber has yet been found! F'riedman, a stu- dent at StuyvesantHS,, plans on majoring, in computer science at the Massachusetts Institute of Technology. The winners of fourth through sixth places are each awarded S7S001scholar- ships. A test of brain hemisphere function while concurrent tasks are perJormed won fourth place for Michael Steven Graziano of Buffalo, N.Y: a student at City Honors HS. His results challenge the'acceptedd theory that when someone performs two tasks at once, the~ tasks are always con- trolled by opposite brain hemispheres: JohmShu-Shin Kuo of 1Vhitestone. N.Y., a student at Bronx High School of Science. was awarded fifth placeior a study of a ge- netic element of a microbe that can jump from one host to another and make ge- netic rearrangements possibie. Sixthplace went to Anthony Mario Ciabarra of Wym- cote. Pa., a student at Cheltenham HS'. He studied an unusual DNA repair mutation which he believes explains mechanisms involved in the action of'carcinogensand viral infections. Scholarships of 55.000 go to the winners of seventh through tenth place: They are Mark Kantro>w•itx of Brookline. Mass., a student at Maimonides School. Michael' William Gesner of Avon. Mass,, a student at 150 Human white blood cells as carcinogens Blood l cells that normally protect the body, from bacterial infection sometimes can produce enough germ-killing toxic substances over a long enough time to cause normal tissue to become maligttanti researchers at Massachusetts General Hospital and Harvard Medical School in Boston report in the: March, 8 Sa>FNCS. They believe some cancers can be caused not only by toxic substances in the envi- ronment but also by toxic substances re- leased by cells called phagocytes to lend off environmental!earcinogens.. The researchers showed that human neutrophils - phagocytic white blood cells that ingest bacteria and foreign sub• stances-release toxic free radicals (oxy- $en metabolites) that can cause normal mouse connective tissue: to become malignant. They injected 43' mice with cells treated with human neutrophils acti+ vated to produce toxic oxygen metabo• lites and injected a control group of 53 mice with untreated cells: Five of the mice given, treated cells developed malignant tumors and six developed benign tumors. None of t'he control mice developed tumors. Humans need phagocytes to protect against bacteria in the environment. The body has several' elaborate chemical mechanisms to detoxify phagocytesl oxy- gen products; -but it's a relative resis- tance: says Sigmund VlJeit:man: who di, rected'the research. -If there are too many of these metabolites, they can damage normal tissue' The most common human model in which phagocytes accumulate and ulti- mately cause cancer is ulcerative volitis. a chronic bowel inflammation. After about 20 years of constant bathing with toxic phagocytic prod'ucts, colorectal cancer may result. The researchers believe the mechanism of phagocytic accumulation and produc- tion of toxic metabolites.mightalso help explain the origins, of! lung and breast cancer People who smoke gather particles of soot and nicotine in their Iungs: Phago- cytes then accumulate and release their toxic products. which may interact with the chemicalicarcinogens in cigarettes to cause lung cancer, says Thomas P. Stossel, an author of the paper. The mechanism's role in breast cancer is more tenuous, Stossel say,s. Female breast tissue is regenerated every monthh as cells of'breast ducts are replaced by new ones. Phagocytes are called!in to get rid of, the degenerating cells. releasing their-nasty chemieals- in the process. Re- peated exposure to toxic phagocytic products over timecould contribute tothe development of breast cancer, Stossel says: The researchers do not know the spe- cific molecules ultimately responsible for causing normal tissue to become malig.- nanC: Phagocytes produce superoxide. hy- drogen peroxide and hydroxyl iradicafs. as well as other toxic substances.These sub- stances can interact with membranecom- ponents of phagocytes or, their, targetcells to generate other toxic products. such as peroxides and aldehydes. Although earlier work suggests an important, role for hy- droxyl radicals in the overall process, ac- cording to the SctttNt:E paper-the ultimate carcinogen remains to be definedl' D Bennett 20~2'~1!181 SCIENCE NEWS, V0,12'