A Place for Prions
We previously discussed the bizarre infectious proteins called prions in the context of kuru, the disease of muscle tremors and uncontrollable laughter spread by cannibalistic rituals in Papua New Guinea. In diseases such as kuru or mad cow disease, abnormal prion proteins wreak havoc by binding to native prions and other cellular elements, creating clumps that kill off cells in the nervous system. But one important thing I didn’t mention in the kuru article – nobody’s really sure what the native, normal prions actually do!
That mystery may have been somewhat dispelled by an article published by Nature Neuroscience last weekend from a team of scientists in Sweden and Germany. Those researchers knocked out or interrupted the gene for prions in a number of different mouse strains, a strategy that had previously yielded a pretty normal mouse without much to say about the prion’s purpose. But for the current experiment, the researchers were patient, allowing the mice to live to the grand old age of 60 weeks (mice typically live for about two years) before looking for deficiencies related to their lack of prions.
What they found in their elderly mice links back to another ScienceLife post – peripheral neuropathy, a motor disorder marked by the demyelination of peripheral neurons. The nerve cells running from the spinal cord to muscles of the prion-free mouse’s body were normal, save for a thinned-out sheath of myelin along the axon. As discussed previously for multiple sclerosis (where central nervous systems neurons are demyelinated), this loss of myelin leaves cells less insulated and like a frayed power cable, unable to transmit signals at optimum speeds. Hence, the motor difficulties associated with peripheral neuropathy, which in humans manifests itself as twitching, paralysis, and loss of dexterity.
That could be a promising finding for not just one field but two. Recall that motor difficulties are usually one of the first symptoms of prion diseases – “kuru” is the word for “shiver” in the Fore language of Papua New Guinea’s Eastern Highlands. Prion gene knockout mice may have their issues, but have the small consolation of being resistant to prion diseases. And the study of peripheral neuropathies (plural, because the term covers several different diseases) could benefit from the new identity of the prion as a mediator of myelin maintenance.
How Not to Do Research
The 1998 paper was key evidence for the crowd that believes vaccinations can cause autism…even after it was debunked. Andrew Wakefield, at the time a gastroenterologist at a London hospital, published in the prestigious medical journal The Lancet a small study showing an association between the measles, mumps, rubella (or MMR) vaccine, irritable bowel disease, and “developmental disorder.” That observation was extrapolated, with the help of the author and gullible media, into proof that vaccines can cause autism, a thoroughly unsupported conclusion that nevertheless was influential enough to put a dent in British vaccination rates.
In 2004, that paper was retracted by The Lancet and Wakefield’s co-authors for both ethical and scientific malfeasance, but Wakefield continued to hype its results in the UK and US. Yesterday, Wakefield was formally sanctioned by the General Medical Council, the regulatory body for doctors in the UK, for misleading, dishonest and irresponsible conduct in his research and subsequent promotion. The details, described fully in the GMC report, are appalling – unnecessary invasive procedures on child subjects, consultations with lawyers looking to launch lawsuits against vaccine makers, unreported subject bias. One would like to think that this would finally put an end to the vaccination myth, but the sad fact is that debunking scary pseudoscience claims garners far less attention than proliferating them. So here I am, blogging about it!
(By the way, if you haven’t already read Trine Tsouderos’ latest article in her series on ghastly, unscientific treatments for autism in the Chicago Tribune, see this one about an industrial chelator being marketed as a safe “nutritional supplement.”)
Famous insect biologist E.O. Wilson publishes “Trailhead,” an excerpt from his upcoming novel – yes, novel – in The New Yorker. It’s a fascinating inside-the-anthill POV story about a dying ant colony and the complex behavior within, and I loved it, despite the fact that it made me feel like I had ghost ants all over me while I read it.
Again to the New Yorker for an interesting profile of Elizabeth Kubler-Ross, the psychologist who came up with the “stages of grief” theory…and was conspicuously not rehired by our very own Billings Hospital over her controversial research.
Paleontologists confirm using cellular imaging that some dinosaurs had reddish-orange colored tails. UChicago’s Paul Sereno was quoted by the Associated Press theorizing that skin color in dinosaurs may have developed for the similar evolutionary reasons as the colorful feathers of peacocks.