The neuroanatomical basis of meridian effects is one of the focuses of acupuncture mechanism studies. Meridian effects depend mainly on the generation, conduction, integration and output of acupuncture information in the acupoint, spinal cord and brain.The neural tracer technique is a basic method in neurobiology. This article presents recent years' advances in the application of the neural tracer technique to acupuncture field and summarizes the types of neural tracer used in acupuncture studies and regularities in the distribution of neurons and their fibers related to labeled meridians and acupoints in spinal segments and brain regions to provide methodological reference for studies on neurobiological mechanism of acupuncture effects.

Objective To investigate the influencing factors for direct-acting antiviral agent (DAA) therapy failure in the treatment of hepatitis C by comparing baseline clinical data and resistance-associated substitution (RAS) in sequencing data between the patients with HCV RNA reactivation after DAA therapy and the patients with successful DAA treatment. Methods A total of 13 patients from multiple centers who failed DAA therapy from November 2019 to October 2021 were enrolled as treatment failure group, and sequencing was performed for their positive serum samples. A total of 51 patients with successful DAA treatment were enrolled as control group, and baseline clinical data and sequencing results were compared between the treatment failure group and the control group. The Mann-Whitney U test was used for comparison of non-normally distributed continuous data between groups, and the chi-square test was used for comparison of categorical data between groups; univariate and multivariate logistic regression analyses were performed to calculate odds ratio ( OR ) and investigate the influencing factors for treatment failure. Results All 12 patients with complete treatment data experienced recurrence within 1 year after the end of medication. The male patients with treatment failure had significantly higher baseline total bilirubin, direct bilirubin, and creatinine than their female counterparts ( Z =-2.517, -2.440, and -2.132, P =0.010, 0.010, and 0.038), and the patients with an age of ≤55 years ( OR =5.152, 95% confidence interval [ CI ]: 1.116-23.790, P =0.036) or genotype 3b ( OR =9.726, 95% CI : 1.325-71.398, P =0.025) had a higher probability of treatment failure. There were differences in the incidence rates of major RAS mutations on three gene fragments between the treatment failure group and the treatment success group, and the common RAS mutations detected in the treatment failure group were not detected in the treatment success group. Conclusion Age, genotype, and RAS in serum virus gene sequence are influencing factors for DAA treatment failure.