- T4: 48 ± 6 hours after the end of surgery (control blood count). On these blood samples, it will be assessed the degree of DNA methylation. The samples will be subjected to extraction of RNA and genomic DNA through ZR-Duet ™ kit DNA / RNA Miniprep (Zymo Research). The nucleic acids obtained from the samples will be stored at - 80 ° C until analysis.