The effect of transversus abdominis plane block on the chronic pain after colorectal surgery: a retrospective cohort study.

BACKGROUND: Chronic postsurgical pain (CPSP) is common and would reduce the quality of life of patients. Transversus abdominal plane (TAP) block has been widely used in lower abdominal surgery and many researches demonstrated that it could improve acute postsurgical pain. We aim to determine whether TAP block could improve chronic postoperative pain at 3 months and 6 months after colorectal surgery. METHODS: A total of 307 patients received selective colorectal surgery under general anesthesia between January, 2015 and January, 2019 in a single university hospital were included: 128 patients received TAP block combined with patient-controlled intravenous analgesia (PCIA) for postsurgical analgesia (group TP) and 179 only administrated with PCIA (group P). Main outcome was the NRS score of pain at 3 months after colorectal surgery. The data was analyzed by two-way repeated measures anova and the chi-square test. RESULTS: The NRS score at rest and during movement was decreased significantly at 24 h after surgery (rest NRS 1.07 ± 1.34 vs 1.65 ± 1.67, movement NRS 3.00 ± 1.45 vs 3.65 ± 1.89; all P = 0.003) in group TP than those of group P. There was no significant difference of NRS score at 48 h after surgery (P > 0.05). At 3 months after surgery, the NRS score during movement was also lower in group TP than that in group P (0.59 ± 1.23 vs 0.92 ± 1.65, P = 0.045). There was no significant difference of NRS score at 6 months after surgery (P > 0.05). The prevalence of CPSP was 19.5% (25/128) in group TP and 20.7% (37/179) in group P at 3 months after surgery. 13.2% (17/128) of patients suffered from CPSP in group TP and 13.9% (25/179) in group P at 6 months after surgery. Both at 3 months and 6 months after surgery, there was no statistical difference of the prevalence of CPSP between the two groups (all P > 0.05) . CONCLUSIONS: TAP block reduced NRS during movement at 3 months after surgery but did not reduce the incidence of CPSP at 3 months and 6 months after selective colorectal surgery.

Organic anion transporting polypeptide 1A2 mediates fentanyl uptake in cultured cells.

Individual differences in the response to fentanyl, which may be caused by different concentrations of the drug in the central nervous system, can complicate analgesic treatment. It has been reported that the organic anion transporting polypeptide (OATP) at the blood­brain barrier (BBB) in Sprague­Dawley rats may serve an important role in the transport of fentanyl across the BBB. However, whether human OATP can transport fentanyl has thus far not been reported. The present study aimed to establish a 293 cell line stably overexpressing OATP1A2, and to determine whether OATP1A2 is able to transport fentanyl across the plasma membrane. Initially, 293 cells were transfected with an OATP1A2­expressing plasmid (referred to as 293­OATP1A2 cells), and single colonies were selected and characterized following geneticin treatment. Subsequently, reverse transcription­quantitative polymerase chain reaction and western blot analyses were conducted to verify the transfection efficiency. Furthermore, treatment of 293­OATP1A2 cells with different concentrations of fexofenadine (FEX) and fentanyl was performed to investigate the transport function of OATP1A2 in 293 cells. FEX and fentanyl uptake experiments were also performed with naringenin, an inhibitor of OATP1A2. The results indicated that FEX and fentanyl uptake was significantly increased in 293­OATP1A2 cells compared with that in the control­transfected cells. The 293­OATP1A2­mediated uptake of FEX at concentration of 100 nM FEX was ~10­fold higher than that of 293­VC cells. The 293­OATP1A2­mediated uptake of fentanyl (100 nM) was 5.1­fold higher compared with that in 293­VC cells. In 293­OATP1A2 cells, the uptake of FEX without OATP1A2 inhibitor naringenin (100 µg/ml) was 2.8­fold higher compared with that in the presence of naringenin, and the uptake of fentanyl without naringenin was 7.3­fold higher compared with that in the presence of naringenin (100 µg/ml). In conclusion, 293 cells that overexpressed OATP1A2 were successfully constructed, and OATP1A2 was revealed to mediate fentanyl uptake in the cultured cells.

Analysis of synonymous codon usage in enterovirus 71.

Enterovirus 71 (EV71) is the major cause of hand-foot-and-mouth disease in children. In our study, using the complete genome sequences of 42 EV71 representing all three genotypes, we analyzed synonymous codon usage and the relative dinucleotide abundance in EV71 genome. The general correlation between base composition and codon usage bias suggests that mutational pressure rather than natural selection is the main factor that determines the codon usage bias in EV71 genome. Furthermore, we observed that the relative abundance of dinucleotides in EV71 is independent of the overall base composition but is still the result of differential mutational pressure, which also shapes codon usage. In addition, other factors, such as hydrophobicity and aromaticity, also influence the codon usage variation among the genomes of EV71. This study represents the most comprehensive analysis of EV71 codon usage patterns and provides a basic understanding of the mechanisms for codon usage bias.