ADVERTISEMENT
See Inside March 2008

Letters

Environment and ALS -- The Genetic Code -- Vitamin D

Lifestyle Link?
“Playing Defense against Lou Gehrig’s Disease,” by Patrick Aebischer and Ann C. Kato, was an excellent and hopeful summary of current research on amyotrophic lateral sclerosis (ALS). But the last paragraph, which suggests that lifestyle may play a role in the development of ALS (and which mentions that regular exercise offers some protection against neurodegenerative diseases), seems to have little to do with the research described in the article.

Many of those affected by ALS tend to be fit, lean, active people who lead a healthy life. This lean-active correlation is more likely an effect than a cause: something about various genetic predispositions may also tend to militate against becoming sedentary. And the epidemiological studies of ALS that have been done—albeit with small samples—have so far found that the only environmental factors to have any correlation are increased age, being male and participating in the first Gulf War.

Although lifestyle may be a factor to investigate, the fact that about 50 percent of motor neurons can die before symptoms become noticeable makes it more likely that the most effective approach to treatment and a cure will be to find a set of reliable biomarkers that can diagnose the problem and its specific starting event or events years earlier and to develop a cocktail of appropriate drugs to direct at the initial and root causes. 

Dougal MacDonald
Edmonton, Alberta

Code Crack Credit
In asserting Marshall W. Nirenberg as the discoverer of the genetic code, “The Forgotten Code Cracker,” by Ed Regis [Insights], might lead an unwary reader to conclude that Francis Crick considered himself to have discovered it. Such an inference should be checked against the available records in the Crick Papers at the Wellcome Library in London. There one  can find correspondence in which Crick, referring to the “fuss” made by the British press over his and his colleagues’ 1961 Nature article establishing major features of the genetic code, reassures Nirenberg “that it is your discovery which was the real breakthrough.”

The issue of priority was still a concern for Crick when Scientific American was to publish review articles by both him and Nirenberg, in that order. Crick stressed to the editor that he should not be published first, as “it should not appear to anyone that we wish to claim more than is our due. However ingenious and elegant our experiments are, it must be realized that it is the biochemical work on the cell-free system which will be crucial.” Crick also explained that Nirenberg and Johann Matthaei’s basic discovery came before Crick and his colleagues received the triple mutants that clinched their own conclusions. These reservations surely support the view that he would not have wanted to be called the discoverer of the code.

Robert Olby
University of Pittsburgh

WHITE REPLIES: Tanning lamps are not equivalent to UV radiation. Such lamps are generally a much stronger source of UVA light and a weaker source of UVB light than the sun. (It is only the latter that induces cutaneous vitamin D synthesis.) Certain manufacturers claim to offer portable UV sources designed to generate UVB, but I do not know much about them.

In any case, vitamin supplements present a safer option. (In Montreal, I personally take 4,000 inter­national units of Vitamin D3 daily from October until mid-May, when it becomes warm enough to be outside in shirtsleeves.) You should also have your 25-hydroxyvitamin D levels checked: ideally they should be close to 50 nanograms per milliliter (and at least 40 ng/ml).

Wasteful Warheads
“Build Diplomacy, Not Bombs” [Perspectives] was right on about the unnecessary nature of a program to replace nuclear warheads. We are financing far too many government programs just to keep a few scientists and other high-paid employees available and trained in case there is ever a need for their outdated services. In my experience as a government engineer, I found that the differences of opinion among scientists advocating mission callback capabilities, hardened missile sites and highly mobile launch vehicles used up a huge amount of our tax-supported resources.

Rights & Permissions
Share this Article:

Comments

You must sign in or register as a ScientificAmerican.com member to submit a comment.
Scientific American Special Universe

Get the latest Special Collector's edition

Secrets of the Universe: Past, Present, Future

Order Now >

X

Email this Article

X