Statistical Analysis
Statistical analysis was performed using SPSS BASE 17.0 statistical
software (SPSS Inc. Chicago, IL, USA). Categorical variables were
expressed as percentages and compared using the Chi-square or Fisher’s
exact test, as appropriate (n ⩽ 5 per group). Continuous variables were
expressed as mean ± 1 standard deviation and were compared using the
Student’s t test. A two-tailed p-value less than 0.05 was taken to
indicate statistical significance.