Letters.

Better for whom?

I am concerned about the use of agents that boost apoptosis (programmed cell death) to fight cancer--substances such as conjugated linoleic acid ("Better butter? This one may fight cancer," SN: 12/11/99, p. 375) and genistein from soybeans. Does it not stand to reason that accelerating apoptosis might have negative effects on the body? I think we need to tread very carefully when we're talking about what amounts to long-term, low-level chemotherapy.

Scott L. Burson Santa Cruz, Calif.

Because butter appears to inhibit cancer in rats does not necessarily mean that it will do so in any other species, even mice. For that reason, I'm more hopeful of seeing replacement corneas grown from human cells ("Laboratory-grown corneas come into sight," SN: 12/11/99, p. 374) than seeing butter designated a health food for humans.

Bina Robinson Swain, N.Y.

In the "better butter" article, the benefit of linoleic acid as a potent anticancer agent is emphasized. The article also discusses means to increase conjugated linoleic acid by supplementing a cow's diet with sunflower oil. In letters ("Oil all over," SN: 12/11/99, p. 371), there are these statements: "linoleic acid, the primary fat in corn oil, can fuel the growth of cancer in animals" and "linoleic acid is also the primary fat in sunflower ... oil."

I would appreciate clarification of the apparent contradictions.

James R. Baker Odenton, Md.

Conjugated linoleic acid is a structural variant of ordinary linoleic acid. In conjugated linoleic acid, only one single bond separates a pair of double bonds that in ordinary linoleic acid are separated by two single bonds. Though small, this change accounts for the very different pharmacological properties of the fatty acids. --J. Raloff

Computer memories

"Simplicity makes for superfast computing" (SN: 12/11/99, p. 373) tells of a processor that "would be able to handle eight tasks at once." This unique approach to processor design was invented 30 years ago and was reduced to hardware, with over 50 such systems being built and distributed. Two patents were issued in 1975. The computer systems, designed and built for Memorex Corp., were called the MRX50. One of the tests was to program the computer to handle eight disparate computing tasks at the same time with no task switching. Unfortunately, further application of these ideas at that time was forestalled.

Donald H. Malcolm Brooklyn Center, Minn.

Who's resistant?

Has it really been discovered that dead people can benefit from later genetic changes? Your article ("Survivors' benefit?" SN: 1/22/00, p. 63) closed with this: "The ancestors of those survivors [of ancient smallpox epidemics] ... now enjoy the added benefit of resistance to HIV."

Jim Cahill West Branch, Iowa 

Oops. It should have been descendants.

--The Editors