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Science: Nose tissue may provide Alzheimer's test

Science: Nose tissue may provide Alzheimer's test

作者:褚浯绵  时间:2019-02-26 07:13:00  人气:

By SUSAN HULME A PROJECT to develop a test for the early stages of Alzheimer’s disease is to be launched at the University of Sussex later this year. As a first step, researchers will collect samples of the lining of the nose from people suspected of having Alzheimer’s. Recent research carried out in the US suggests that certain nasal tissue – the olfactory epithelium – shows distinctive signs when people have the disease (New Scientist, Science, 11 March 1989). When a person develops Alzheimer’s disease, nerves in the central nervous system degenerate, resulting in distinctive features in the brain known as plaques and tangles. But research into the treatment of the disease has been paralysed by the lack of a diagnostic test: the cells of the central nervous system are inaccessible. At present, changes due to Alzheimer’s can be detected only by a brain autopsy once the person is dead. In living patients, Alzheimer’s is diagnosed by assessing the level of dementia, and by a brain scan, procedures that may not be accurate. Last year, however, Barbara Talamo and her colleagues at a number of institutes, including Tufts Medical School and the New England Medical Center, both in Boston, Massachusetts, made the discovery that Alzheimer’s disease has a noticeable effect on the neurons in nasal tissue. It changes their shape, their distribution, and the relative abundance of proteins they contain. The researchers suggested that it would be possible to remove tissue from a patient easily, under a general or even a local anaesthetic. Lynne Mayne and her colleagues at Sussex University’s Trafford Centre for Medical Research are starting a community study on a much larger scale than the research programme in the US: they expect to study several tens of patients a year, rather than the nine of the American study. They will take a sample of nasal tissue from any Alzheimer’s patient who is undergoing surgery, for any reason. The researchers are also asking patients or their relatives to allow them to take a sample of nasal tissue within hours of a patient’s death. Speed is important because nerve cells degenerate very quickly. GPs will be asked to take a nasal sample from any patient with Alzheimer’s who dies. Mayne and her colleagues intend to compare the nasal tissue with brain tissue, and with similar samples taken from healthy people. They want to find out whether people with Alzheimer’s can be distinguished from those with other forms of dementia by their nasal tissue alone. The sensory neurons high up in the nose are unique among nerve cells because they regenerate throughout adult life. They are also the only cells of the central nervous system that can be sampled during life. If a test can be developed, it will be important because current methods of diagnosing Alzheimer’s disease are not accurate enough to assess the potential of possible drugs. Another drawback is that it is impossible to diagnose the disease until it is well advanced, when damage may be too extensive for treatment by potential drugs. According to Mayne, people coming to their doctors for the first time with symptoms usually have problems with coordination. By then, a large number of neurons have been lost. ‘The value of a diagnostic test,’ says Mayne, ‘is that it could pick up the disease before the neurons have been lost.’ Mayne and Ruth Maxwell at the Trafford Centre hope to grow cells of the central nervous system from healthy people and people with Alzheimer’s in culture. Under controlled in vitro surroundings, they then intend to subject the cells to a battery of environmental influences – such as aluminium in water – which have been linked with the genesis of Alzheimer’s disease. They hope that this will allow them to examine the way the neurons degenerate more systematically. Most researchers agree that nasal tissue could yield more information about Alzheimer’s disease. But some believe that it is not the best practical test in the pipeline. Gordon Wilcock, of the University of Bristol, a founder of the Alzheimer’s Disease Society, says ‘I think patients will be much happier to have their skin biopsied than their noses,’ says Wilcock. ‘I have a feeling that the epithelial story is very interesting and may be a useful tool for research,