Two years: That’s how long it took a PLOS journal to flag a paper after a sleuth raised concerns

Two years after being alerted to a questionable figure in a 2016 paper by a group with a questionable publication history, a PLOS journal has issued an expression of concern about the article.

The paper, “Deprivation of L-Arginine Induces Oxidative Stress Mediated Apoptosis in Leishmania donovani Promastigotes: Contribution of the Polyamine Pathway,” was published in  PLOS Neglected Tropical Diseases and was written by a team based at the ​​Rajendra Memorial Research Institute of Medical Sciences in Patna, India, along with a few other institutions in that country.

The penultimate author of the paper is Chitra Mandal, of the CSIR-Indian Institute of Chemical Biology in Kolkata. Mandal’s name appears dozens of times on PubPeer, where posters have flagged the figures in her papers. In a 2019 article in The Hindu, Mandal hinted that an institutional investigation into her work was underway but she dismissed the problems as “unintentional minor mistakes”:

Moreover, this matter has already been discussed with the highest scientific body. Such a high-level scientific committee will look at these unintentional human technical errors. I would strongly say that these unintentional minor mistakes do not alter the major scientific outcome and information from these experiments.

To date, Mandal — who has received numerous awards and honors, including the Sir J.C. Bose Fellowship from the Department of Science and Technology — has lost three papers to retraction by our count: a 2012 article in PLOS ONE, a 2019 paper in the same journal, and a 2009 article in Infection and Immunity for which a notice doesn’t seem to be available.

In June 2019, the data sleuth who goes by the pseudonym “Clare Francis” informed PLOS about what they believed were suspect similarities in Figure 6 of the article — issues that comments, most of which were by Francis, on PubPeer echoed.  

Then silence, until July 2021, when Maria Zalm, PLOS’ senior editor for publication ethics, contacted Francis by email, apologizing for the lack of communication and providing a link to the expression of concern. Of the 26 times the paper has been cited, according to Dimensions,

42% of its citations have been received in the past two years, which is higher than you might expect, suggesting that it is currently receiving a lot of interest.

A lot of interest, but perhaps not the kind of interest the authors were hoping for. According to the notice: 

Following the publication of this article [1], concerns were raised regarding results presented in Fig 6. Specifically,

— The results presented for the 72 hr AD-Ld/Orn+, 72 hr AD-Ld/Put+, 72 hr AD-Ld/NAC+, and 96 hr AD-Ld/NAC+ appear similar but not quite identical.

— The results presented for the 120 hr AD-Ld/Orn+ and 120 AD-Ld/Put+ results appear similar but not quite identical.

The authors submitted higher resolution versions of the panels presented in Fig 6, provided in the S1 File below. A member of the PLOS Neglected Tropical Diseases board assessed the concerns and the data provided by the author and indicated that the higher resolution images highlight minor differences between the 72 hr AD-Ld/Orn+, 72 hr AD-Ld/Put+, 72 hr AD-Ld/NAC+, and 96 hr AD-Ld/NAC+ panels, but that the 120 hr AD-Ld/Orn+ and 120 AD-Ld/Put+ panels appear more similar than would be expected from independent samples.

The raw flow cytometry data underlying the panels presented in Fig 6 are no longer available. In the absence of the original data underlying Fig 6, PLOS Neglected Tropical Diseases cannot confirm the reliability of the results presented in this figure.

The raw data and individual level data underlying the other results presented in this article are no longer available.

The PLOS Neglected Tropical Diseases Editors issue this Expression of Concern to notify readers of the above concerns and relay the higher resolution figures provided by the corresponding author.

Neither Mandal nor the corresponding author, Pradeep Das, returned a request for comment.

PLOS is no stranger to long lags in resolving concerns about the articles it publishes, as we’ve reported — delays the journal has attributed in the past to staffing shortfalls and an invigorated effort to root out untrustworthy papers. 

Update, 1400 UTC, 7/22/21: About the expression of concern, Mandal tells Retraction Watch:

Yes, it is unfortunate that in Figure 6 certain controls were duplicated. Although data pertaining to this figure was not generated in my group, I accept responsibility as a co-author. It was an avoidable error.

Asked about the dozens of papers flagged on PubPeer, Mandal said:

In discussion with other co-authors, majority of whom were my doctoral students, we communicated with the journals and addressed most of the pubpeer comments, as many of them were purely technical and the data had been misinterpreted.

Our explanations to the respected editors were accepted and the journal informed us that nothing further needs to be done.

In a few papers, there were inadvertent errors in sections of a figure, but as the scientific hypothesis/observations were supported by several approaches, the scientific inferences of these publications remained unchanged.

The journals allowed us to publish the corrected figure as a corrigendum.

Other decisions can be seen in Pubpeer.

Asked about the existence of an institutional investigation, Mandal said:

An investigation was immediately initiated and is still ongoing, the delay being primarily due to the ongoing COVID-19 pandemic.

Asked whether any other papers were slated for retraction, Mandal said:

To the best of my knowledge, no paper is currently being considered for retraction.

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