Above is a photomicrograph of the spinal cord terminal of a sensory axon. The neuron's immunoreactivity for human preproenkephalin suggests that the preproenkephalin gene, which was delivered via a herpes virus vector, is being expressed in sensory neurons.
TELOMERE TROUBLES Lack of telomerase makes mice old before their time, a new study shows, but what effect this might have on age-related disease remains uncertain (K.L. Rudolph et al., "Longevity, stress, response, and cancer in aging telomerase-deficient mice," Cell, 96:701-12, March 5, 1999). Telomerase is a key enzyme in making telomeres, protective elements at the ends of chromosomes. Mice deficient in telomerase have shorter-than- normal telomeres that crumble when cells mature and divide, leading more quickly to cell senescence. The study indicates that knockout mice in generations bred for the shortest telomeres tend to develop tumors more often than normal, respond less well to wounds and loss of blood,...

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