To the Editor:

We are grateful to Dr. Karapolat for his interest in and comments regarding our paper.

We completely agree with the statement "Due to ethical issues, the number of animals to be used in experimental studies should be reduced to the minimum required to make a statistical analysis and yield scientifically reliable and valid results." However, since some of our results revealed excessive variation, it would not have been possible for us to show statistically significant differences with smaller animal groups. If we had used isogenic rodents, it is likely that the results would have been more homogeneous, and that the sample size could have been smaller. Nevertheless, due to the conditions in our laboratory at that time, we chose to use hamsters, which are generally more resistant to infections and tracheal manipulation than are mice.

We believe that the statistical tests employed in the analysis of the results of that study were appropriate. In addition, all efforts were made to control the experimental conditions and proceedings. Unfortunately, variation is an inherent attribute of biology.

Adopting measures to avoid the impending suffering of animals is as important as limiting their number in an experiment. In this regard, we are entirely convinced that every hamster employed in the study was handled with great care in order to avert any potential discomfort and pain.


José Antonio Baddini Martinez
Associate Professor.
Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo - FMRP/USP, University of São Paulo at Ribeirão Preto School of Medicine - Ribeirão Preto, Brazil