As far as I can tell, the British Journal of Pharmacology has taken to requiring that authors who use animal subjects conduct their studies in accordance with the "ARRIVE" (Animals in Research: Reporting In Vivo Experiments) principles. These are conveniently detailed in their own editorial:
McGrath JC, Drummond GB, McLachlan EM, Kilkenny C, Wainwright CL.Guidelines for reporting experiments involving animals: the ARRIVE guidelines.Br J Pharmacol. 2010 Aug;160(7):1573-6. doi: 10.1111/j.1476-5381.2010.00873.x.
Kilkenny C, Browne W, Cuthill IC, Emerson M, Altman DG; NC3Rs Reporting Guidelines Working Group.Animal research: reporting in vivo experiments: the ARRIVE guidelines. Br J Pharmacol. 2010 Aug;160(7):1577-9. doi: 10.1111/j.1476-5381.2010.00872.x.
The editorial has been cited 270 times. The guidelines paper has been cited 199 times so far and the vast, vast majority of these are in, you guessed it, the BRITISH JOURNAL OF PHARMACOLOGY.
One might almost suspect the journal now has a demand that authors indicate that they have followed these ARRIVE guidelines by citing the 3 page paper listing them. The journal IF is 5.067 so having an item cited 199 times since it was published in the August 2010 issue represents a considerable outlier. I don't know if a "Guidelines" category of paper (as this is described on the pdf) goes into the ISI calculation. For all we know they had to exempt it. But why would they?
And I notice that some other journals seem to have published the guidelines under the byline of the self same authors! Self-Plagiarism!!!
Perhaps they likewise demand that authors cite the paper from their own journal?
Seems a neat little trick to run up an impact factor, doesn't it? Given the JIT and publication rate of real articles in many journals, a couple of hundred extra cites in the sampling interval can have an effect on the JIT.