Prominent German diabetes researcher Kathrin Maedler has issued corrections on two papers, and told Retraction Watch she is in the process of defending the data on others.
14 of her papers have been critiqued by PubPeer commenters. The commentary, which spans from her graduate work in 2002 to a 2014 publication in Nature Medicine, includes questions about image manipulation and self-plagiarism.
Here’s a comparison between figures in Maedler’s 2009 PLoS One paper, “Deletion of the Mitochondrial Flavoprotein Apoptosis Inducing Factor (AIF) Induces β-Cell Apoptosis and Impairs β-Cell Mass,” and one she co-authored in 2006 in Diabetes, “Low concentration of interleukin-1beta induces FLICE-inhibitory protein-mediated beta-cell proliferation in human pancreatic islets,” via PubPeer:
Most of the data supporting this novel hypothesis have been generated by one research group [Maedler’s], and based on these findings, a clinical trial has been initiated using interleukin-1 receptor antagonist (IL-1ra) to prevent B-cell death in type 2 diabetic patients. Of concern is, however, that other groups have failed to reproduce in rodent models the key findings of this unifying hypothesis for B-cell death in diabetes.
We asked Maedler about these issues. She told us about this correction published in November in Diabetes, for “Transcription Factor 7-Like 2 Regulates β-Cell Survival and Function in Human Pancreatic Islets,” which reads:
The authors of the above-cited work have noticed that one actin panel, which was used to confirm similar protein loading across the Western blot gel, was mistakenly used in Fig. 5D. At the time of publication, many similar experiments were done, and Western blot analyses of TCF7L2 upon upregulation by TCF7L2 overexpression were performed. Corresponding actin blots were very similar and thus were mistakenly switched.
The figures below show the initial Fig. 5D, as well as the original blots of the whole experiment together with the correct actin blot, which corresponds to the respective experiment. TCF7L2 as well as Caspase-3 blots were correct and remain unchanged.
The authors apologize for the mistake and any inconvenience it may have caused the readers.
The paper has been cited 135 times, according to Thomson Scientific’s Web of Knowledge.
She also told us that a correction to this PLoS ONE paper will be out in the next week or so. That paper has been cited 13 times.
As for the other papers, she said that her lab could prove that the data was correct, but due to her lab moving twice since 2008, it will take some time.