Screening compounds
An incorrect statement appears in your article “Enlisting combichem to fight cancer” (February 2001, p 28). On page 30, the sentence reads: “From 1990 through 1997, John Weinstein’s NCI research group had screened more than 60,000 compounds against a panel of 60 human cancer cell lines.”

In fact this screening program was conceived of, and to this day is directed by, the Developmental Therapeutics Program, Division of Cancer Treatment and Diagnosis, NCI. Dr. Edward Sausville directed our Program from 1989 to 1994, and Dr. Michael Grever from 1994 to the present day. We do collaborate with Dr. Weinstein’s research group on various analyses of the cell panel. However, his group is not involved in the acquisition of potential anticancer agents for this screen, the operation of the screen, or the formal evaluation of the data.

To date, we have evaluated more than 77,000 compounds in the human tumor cell line screen. We make the nonproprietary portion of these data, both structural and biological, available on our publicly accessible Web site (http://dtp.nci.nih.gov), along with data analysis tools for anyone interested in conducting an analysis.

Author’s reply:

I took my information from a Science article entitled “An Information Intensive Approach to the Molecular Pharmacology of Cancer” (Science 1997, 275, 343–349), on which Weinstein was the lead author. Weinstein’s group used the NCI library to identify target molecules, and it would be more correct, as the letter writer points out, to leave Weinstein’s name out of the sentence and change it to read, “From 1990 through 1997, NCI research groups had screened more than 60,000 compounds against a panel of 60 human cancer cell lines.” I apologize for the misleading original version.

Structural fine points
As an old-timer (over 50 years with ACS) and having taught heterocyclic chemistry for more than 50 years, I take strong issue with several of the chemical formulas in the March 2001 issue (News In Brief, p 11). I don’t mind “shortcuts” or new methods of presentation, but you set a poor example when you omit “hydrogens” where I think they count. Witness the structures on page 11 for thiabendazole and theophylline. There has to be a hydrogen, H, on the imidazole type of N as distinguished from the pyridine type of N.

In your presentation of 8-hydroxy-2-deoxyguanosine on page 12, a short “stroke” in organic structures has been used to indicate the presence of a methyl group. In the sugar part of the molecule, at C-2, you show two strokes for the two H’s at that point. Unfortunately, beginning students sometimes confuse those strokes with the attachment of a methyl (CH₃) group. It is best to omit all strokes for H’s in sugar structures. I know this might be nitpicking, but it is not unusual for the carbon bearing the two H’s (no OH) to be left as a corner in the pentagon without the two “strokes”. In that respect, I am glad that the pyrrole N’s in thiabendazole and theophylline did not have a short stroke on them (for the N–H bond), because that could be construed to be a N–Me bond.

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