Briefly . . .

• Worst asthma symptoms caused by prostaglandin D₂
• Pathologic protein gives fruit flies Parkinson's disease

CMAJ 2000;162:1731

The mechanism behind asthma is under increasing scrutiny. In asthma, environmental antigens trigger immunoglobulin E antibodies, which then activate mast cells. These mast cells release substances that induce inflammation. Experiments with genetically engineered mice now show that one of these inflammation-inducing substances — prostaglandin D₂ — is responsible for the worst symptoms of asthma (Science 2000;287:2013-7). When the gene for prostaglandin D₂ receptors was removed from asthmatic mice, they did not experience the hyper-reactive airways typical of asthma. Future therapies targeting prostaglandin D₂ could mitigate asthma's life-threatening complications.

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Researchers have created fruit flies with Parkinson's disease — one of the few animal models of the disease, and proof that a mutant protein leads to the neural degeneration in the disease (Nature 2000;404:394-8). They now hope that the flies will show how the protein works, and provide a testing ground for new therapies. The researchers genetically engineered Drosophila melanogaster to express mutated -synuclein, a protein found in abundance in nerves, whose function is unknown. Two mutations in genes that encode -synuclein were recently found in families with inherited Parkinson's disease, leading to research into the protein. The fruit flies with mutated proteins have physical signs of Parkinson's disease — progressive loss of dopamine-secreting neurons and intracellular aggregates resembling Lewy bodies — as well as behavioural characteristics. The flies failed a standard vial-climbing test, indicating locomotor defects.

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© 2000 Canadian Medical Association or its licensors