Tryptophan is an essential amino acid in all animals. After being metabolized through three pathways in the body, it generates many bioactive metabolites, which affect the physiological processes of the body and provide a basis for potential therapeutic targets of diseases, especially the Kynurenine pathway. This article introduces the roles of the three metabolic pathways of tryptophan in the occurrence and development of ulcerative colitis and colitis-associated colon cancer, with particular attention to the role of the Kynurenine pathway in immune regulation and its potential contradictory effects on ulcerative colitis and colitis-associated colon cancer.

Tryptophan is an essential amino acid in all animals. After being metabolized through three pathways in the body, it generates many bioactive metabolites, which affect the physiological processes of the body and provide a basis for potential therapeutic targets of diseases, especially the Kynurenine pathway. This article introduces the roles of the three metabolic pathways of tryptophan in the occurrence and development of ulcerative colitis and colitis-associated colon cancer, with particular attention to the role of the Kynurenine pathway in immune regulation and its potential contradictory effects on ulcerative colitis and colitis-associated colon cancer.

Objective:To systematically evaluate whether the early use of bracing after posterior lumbar fusion has advantages in terms of the improvement of clinical outcomes such as pain, functional disability, fusion rate, and complication rate in patients with lumbar degenerative diseases.Methods:All randomized controlled trials of bracing performed after posterior lumbar fusion in patients with lumbar degenerative diseases were searched in Pubmed, Web of Science, Embase, China national knowledge infrastructure (CNKI) and Wanfang database from January 1990 to May 2022. The data extracted were authors, year of publication, nationality, subject characteristics, sample size, surgical protocol, type and time of bracing, follow-up duration, preoperative and postoperative Oswestry disability index (ODI) and visual analogue scale (VAS), postoperative fusion rate and complication rate. The Cochrane Risk of Bias tool was used to evaluate the risk of bias. The use of fix- or random-effect models was depended on the magnitude of heterogeneity. Data analysis was performed using Stata 17.0 statistical software for meta analysis.Results:A total of five randomized controlled trials were included, all in English, with a total of 362 patients (male 144, female 218). The results of meta-analysis showed that there was no statistically significant difference in the improvement of ODI scores [ MD=1.25, 95% CI(-2.39, 4.88), P=0.501]and VAS scores[ MD=0.21, 95% CI(-0.22, 0.63), P=0.340]between the brace group and the control group after operation. In terms of fusion rate, there was no significant difference between the brace group and the control group[ OR=0.59, 95% CI(0.25, 1.38), P=0.224]. In addition, there was also no significant difference in the incidence of postoperative complications between two groups[ OR=1.12, 95% CI(0.58, 2.15), P=0.735]. Conclusion:The early use of bracing after lumbar fusion has no significant advantages in improving symptoms and functional recovery, fusion rate and surgical complications. The necessity of postoperative bracing after posterior lumbar fusion requires further high-quality research to prove.