Help from a Bug

E. coli makes a vital hormone

Somatotropin is one of the body's important chemicals. Produced by the tiny pituitary gland at the base of the brain, it promotes normal physical growth, hence its other name, human growth hormone (HGH). The chemical is vital in the treatment of a certain form of dwarfism. Unless children who are deficient in the hormone receive injections of HGH, they rarely reach five feet in height. The supply, however, is severely limited: somatotropin can only be obtained from cadavers, and about 50 of the pea-sized glands are needed to treat just one child for a year (cost: $5,800)

That shortage may soon be eased. In the most dramatic display yet of the controversial genetic engineering technique known as recombinant DNA, independent teams at the University of California in San Francisco and at a small commercial research firm, Genentech Inc., in nearby Palo Alto, used human pituitary tissue to construct the gene, or DNA segment, responsible for the production of somatotropin. They then implanted it in the genetic machinery of a laboratory strain of the common intestinal bacterium Escherichia coli. The gene splicing worked: the re-engineered bugs began to make HGH.

Several obstacles must yet be overcome. Among them: getting the bacteria to produce pure HGH and testing the substance in living creatures, including man. Still, the scientists hope that within two years vats of genetically redesigned E. coli will be acting as minifactories, churning out sufficient somatotropin to treat dwarfism. There may also be enough to test a long held suspicion: that HGH can help heal burns, wounds, bone fractures and even bleeding ulcers.

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