A New Gene for ALS
Amyotrophic lateral sclerosis (ALS) is also known as Lou Gehrig's disease, but you may be more familiar with it as the disease that traps Stephen Hawking's famously brilliant intellect in a nearly non-functional body (see p. 394). Only one causal gene has been identified (SOD1), and it does not appear responsible for the neuronal death that characterizes the disorder. The protein TDP-43, whose function is unknown, is found clumped up in the cytoplasm of brain and motor neurons in ALS sufferers, rather than in the cell nuclei where it should be. Researchers at King's College in London identified a single changed base in the TDPB gene that produces TDP-43; then,looking at additional ALS patients, they found two more mutations in the same gene. In all cases the result was a dysfunction in TDP-43's ability to interact with other proteins. And when a mutated TDPB gene was inserted in chick embryos, some neurons as well as other cells died. Science, Vol 319, 1668-1672.
A New Treatment for Parkinson's
Parkinson's disease is treated by pharmacological dopamine replacement therapy or by electrical deep brain stimulation. But dopamine replacement loses effectiveness over time, and deep brain stimulation is invasive and somewhat risky. In an attempt to remedy these problems, researchers at Duke University applied electrical stimulation to the dorsal column of the spinal cord in mice with Parkinson's symptoms which had been induced either by chemically depleting dopamine or by destroying dopamine neurons. Locomotion increased to 26 times greater than during the 5 minutes prior to stimulation; also, stimulation reduced low-frequency oscillations of neural activity in the striatum that is characteristic of dopamine depletion, and increased higher-frequency activity that typically accompanies normal movement. The researchers suggest that stimulation of the dorsal column, which carries sensory information up the spinal cord to the brain, activates the cortex and increases cortical and thalamic input to the striatum, thus compensating for reduced striatal activity. Science, Vol 323, 1578-1582. See a video showing locomotion in a mouse during stimulation.
