The companies behind clinical trials of blood substitutes that were criticized this year as causing excess deaths are now complaining that one author of a critical article failed to disclose a significant conflict of interest, according to today’s Wall Street Journal.

The author, a researcher at the National Institutes of Health named Charles Natanson, failed to mention that he is one of the inventors of a process that could make the blood substitutes safer. A patent application for the process is pending.

Dr. Natanson told the Journal that he had erred in leaving out that information, but one of his co-authors and a scientist uninvolved in the research defended the critical article’s conclusions.

One of the blood substitutes criticized was PolyHeme, which was the subject of an earlier controversy over whether the design of the clinical trial that tested it was ethical. —Lila Guterman