Statistical analysis
Differences were evaluated for significance (* p ≤ 0.05; ** p ≤ 0.01,
*** p ≤ 0.001) by using the non-parametric one-tailed Mann-Whitney-test
(Prism version 7 for Windows; GraphPad, La Jolla, CA, USA) and a two
tailed Student t-test was used (Prism version 7 for Windows; GraphPad,
La Jolla, CA, USA). Data are shown as mean values + s.e.m. For
correlation of two parameters GraphPad Prism software (version 7 for
Windows) was used.