2.3. Statistical analysis
All analysis were performed in triplicate. Data were analyzed
using Microsoft Excel and the SPSS 17.0 (SPSS Inc., Chicago, IL, USA)
program for Windows. Box-plots were constructed in SPSS graphing
software. The boxes represent the 25th percentile (lower
quartile, lower margin of box), median (solid center line), and 75th
percentile (upper quartile, upper margin of box). The whiskers may
extend up to 1.5 interquartile range of the lower and the upper
quartile and points outside of that (outliers) are represented by
white circles followed by the number of the sample analyzed. The
width of the box indicates the degree of variability in the data. If the
median does not appear near the center of the box, it indicates that
the data are not normally distributed.