Objective The evaluation of lymph node properties before lung cancer surgery has a great impact with the choice of surgical methods.Although there are various examination methods,many methods have invasive or accuracy problems.In order to improve the accuracy of diagnosis,we mainly discuss the value of wide-body spectral CT in the differential diagnosis of mediastinal metastatic lymph nodes,non-metastatic lymph nodes in lung cancer patients and reactive hyperplastic lymph nodes.Methods The clinical and imaging data of 64 patients with lung cancer and 28 patients with pulmonary inflammatory lesions were retrospectively analyzed.All patients underwent plain scan and enhanced dual-phase spectral CT scan.The size,density,three-phase IC,NIC,and λHU of lymph nodes in metastatic,non-metastatic and inflammatory reactive hyperplasia groups were measured on 70 keV single-energy images and iodine-based images,respectively.The single-factor variance and Kruskal-Wallis H rank sum test were used to analyze and compare the differences.Results The short diameter of metastatic lymph nodes was larger than that of non-metastatic lymph nodes and reactive hyperplastic lymph nodes(P<0.001).The plain scan density of reactive hyperplastic lymph nodes was higher than that of metastatic lymph nodes(P<0.001),but there was no significant difference between non-metastatic lymph nodes(P=0.325).The CT values of reactive hyperplastic lymph nodes in arterial phase and venous phase were higher than those of metastatic and non-metastatic lymph nodes(P<0.05).Except for NIC in arterial phase,IC,NIC and λHU in plain scan,IC and λHU in arterial phase,IC,NIC and λHU in venous phase of reactive hyperplastic lymph nodes and metastatic lymph nodes were statistically significant(all P<0.05).There was no significant difference in IC,NIC and λHU between reactive hyperplastic lymph nodes and non-metastatic lymph nodes in plain scan,arterial phase and venous phase(all P>0.05).Conclusion The quantitative and spectral curve slope of iodine in mediastinal metastatic lymph nodes of lung cancer were basically lower than those in reactive hyperplastic lymph nodes.The quantitative parameters of spectral CT had certain diagnostic efficacy in differentiating metastatic lymph nodes and reactive hyperplastic lymph nodes,while the spectral parameters of non-metastatic lymph nodes and reactive hyperplastic lymph nodes were not statistically significant.

Objective To develop deep learning-based auxiliary diagnostic models for diverse pulmonary diffuse cystic diseases,and subsequently evaluate their classification performance to identify the optimal model for clinical diagnosis.Methods A total of 288 patients diagnosed with idiopathic pulmonary fibrosis(IPF),pulmonary lymphangioleiomyomatosis(PLAM),and pulmonary Langerhans cell histiocytosis(PLCH)were prospectively enrolled from the First Affiliated Hospital of Guangzhou Medical University between January 2010 and October 2022,comprising 76 cases of IPF,179 cases of PLAM,and 33 cases of PLCH.A total of 877 CT cases were collected,comprising 232 cases of IPF,557 cases of PLAM,and 88 cases of pulmonary PLCH.Based on the cutoff date of December 31,2019,the CT scans were divided into two datasets:dataset A consisted of 500 CT scans including 185 IPF cases,265 PLAM cases,and 50 PLCH cases;while dataset B comprised 377 CT scans with a distribution of 47 IPFcases,292 PLAMcases,and 38 PLCH cases.The Dataset A was randomly partitioned into training set,validation set,and test set in a ratio of 7∶1∶2.Subsequently,six distinct deep learning neural networks were employed for training after preprocessing and data augmentation.Receiver operating characteristic curves were generated to assess the model performance using metrics such as area under the curve(AUC),accuracy,sensitivity,specificity,and F1 score in order to identify the optimal model.Furthermore,a test set B comprising 30 randomly selected cases from dataset B for each disease type was utilized to evaluate the trained optimal model by employing the same aforementioned metrics.Results In test A,six well-established diagnostic models demonstrated superior classification performance for IPF and LAM,with an AUC greater than 0.9.For LCH,EfficientNet exhibited low classification efficiency with an AUC between 0.6 and 0.7,while Vgg11 showed an AUC between 0.8 and 0.9;the other four models displayed excellent classification efficiency with an AUC greater than 0.9.Except for Inception V3,the remaining five diagnostic models performed poorly in identifying and classifying LCH lesions.Considering multiple indicators,the InceptionV3 model showcased optimal comprehensive performance among the six models,achieving high evaluation parameters such as overall accuracy(94.90%),precision(93.49%),recall(90.84%),and specificity(96.91%).TestB was conducted using the trained InceptionV3 model resulting in an accuracy of 81%,precision of 82%,recall of 81%,and specificity of 90%.Conclusions Six recognition and classification models,developed using deep learning technology in conjunction with pulmonary CT images,demonstrate effective discrimination between LAM,LCH,and IPF.Notably,the model constructed utilizing the InceptionV3 neural network exhibits superior efficiency in accurately recognizing and classifying IPF and LAM.

OBJECTIVE To study the immunotherapeutic effect of chimeric virus-like particles(VLPs) based on hepatitis E virus(HEV) against human papillomavirus type 16(HPV 16) tumor. METHODS HPV16 E7 was inserted into the p239 protein of HEV to form the recombinant chimeric protein p239-HPV16 E7. The constructed recombinant protein was expressed by Escherichia coli, purified, and then refolded, and the protein was detected by electron microscopy and dynamic light scattering to confirm size and shape. Then, the C57B/L mice were immunized with the protein grain, and the lymphocyte differentiation of mouse spleen was detected by flow cytometry and enzyme-linked immune spot immunoassay; in addition, TC-1 tumor cells were used to construct tumor models in C57B/L mice to evaluate the anti-tumor immune effect of protein particles in mice. RESULTS After refold in vitro, the structure of chimeric protein was observed under electron microscopy, and the size of particle was 22.80 nm. The obtained protein particles induced favorable specific cellular immune response in C57B/L mice. Compared with the control group, the proportions of CD3+/CD4+ and CD3+/CD8+ in spleen lymphocytes of experimental groups were significantly different(P＜0.05), and effector T cells secreting IFN-γ interferon were also increased remarkably. At the same time, the obtained protein particles could effectively inhibit the growth of tumor cells in TC-1 tumor-bearing mice, and the mice did not die during the experimental period, while the tumors in the control mice grew rapidly and all died after 6 weeks. CONCLUSION Chimeric protein p239-HPV16E7 which was expressed in prokaryotes can form virus-like particles and effectively induce anti-tumor immunity against HPV16.

Objective: To explore the value of dual-energy CT-based volumetric iodine-uptake (VIU) in the evaluation of chemotherapy efficacy in advanced gastric cancer. Methods: Inclusion criteria of subjects: (1) without previous systematic therapy; (2) with complete clinical information before and after chemotherapy; (3) without contraindications of chemotherapy. Exclusion criteria of subjects: (1) unfinished duration and times of chemotherapy; (2) unmeasurable primary lesions; (3) poor imaging quality or poor gastric filling. Clinical and image data of 52 patients with advanced gastric cancer who were diagnosed by pathology from gastroscopic biopsy, and needed chemotherapy evaluated by imaging and clinical information in the First Affiliated Hospital of Wenzhou Medical University from February 2017 to February 2018 were collected and analyzed. Of 52 patients, 38 were male and 14 were female with the median age of 65 (31-88) years old. All the patients underwent a dual-energy, dual phase-enhanced CT scanning before chemotherapy and after the third chemotherapy session. The parameters of the lesions measured before and after chemotherapy in portal vein phase were as follows: the maximum diameter (the largest diameter among those measured in the cross-sectional, coronal, and sagittal planes), average CT value (the regions of interest were manually pinpointed under cross-sectional planes with largest diameter of the tumor, which did not include regions less than 2 mm to the edge of the tumor) and VIU (lesion volume × iodine concentration). The change rates of maximum lesion diameter, average CT value and VIU before and after chemotherapy were calculated [(post-chemotherapy parameters-pre-chemotherapy parameters)/ pre-chemotherapy parameters]. The efficacy of chemotherapy was evaluated by RECIST 1.1 (the change of maximum tumor diameter after chemotherapy), Choi (the change of average CT value after chemotherapy) and VIU (the change of VIU after chemotherapy), respectively, which was categorized by complete response (CR), partial response (PR), stable disease (SD) and progressive disease (PD). Patients with CR, PR, and SD were assigned to the effective group, while those with PD were classified as the ineffective group. Paired t - test or Wilcoxon signed ranks test was used to compare the changes of parameters before and after chemotherapy, whereas Spearman correlation analysis and Kappa test were used for the correlation analysis and the consistency test between the three evaluation criteria (Kappa≥0.75 indicated good consistency). Results: After chemotherapy, the average CT value [(74.01±16.75) HU vs. (81.06±15.87) HU, t=2.202, P=0.030] and median VIU (668.53×10² μg vs. 272.52×10² μg, Z=4.761, P<0.001) decreased significantly, while the difference of the maximum diameter was not statistically significant [(66.71±34.49) mm vs. (78.45±35.62) mm, t=1.708, P=0.091]. The median change rate of VIU (–53.33%) was greater than that of CT values (–5.75%) with significant difference (Z=-5.408, P<0.001). According to the RECIST 1.1 criteria, 47 patients (90.4%, including 19 with PR and 28 with SD) were effective and 5 patients (9.6%) were ineffective. According to the Choi criteria, 45 patients (86.5%, including 37 with PR and 8 with SD) were effective and 7 patients (13.5%) were ineffective. According to the VIU criteria, 46 patients (88.5%, including 41 with PR and 5 with SD) were effective and 6 patients (11.5%) were ineffective. Efficacy comparison among these three criteria showed no significant difference (χ²=0.377, P=0.828). As compared to RECIST 1.1 evaluation, the proportion of PR evaluated by Choi and VIU was significantly higher (χ²=16.861, P<0.001), whereas the proportion of SD was significantly lower (χ²=24.089, P<0.001). There was no significant difference in the proportions of PR and SD between VIU and Choi criteria (χ²=0.887, P=0.346). Consistency and correlation analysis showed that the VIU and Choi evaluation criteria presented the highest consistency and correlation (Kappa=0.912, P<0.001; r=0.916, P<0.001). Conclusion VIU is a feasible parameter for the evaluation of chemotherapy efficacy in advanced gastric cancer, and may be more sensitive than the evaluation criteria based on maximum diameter or change of CT value in the tumor.

Objective To explore the value of dual?energy CT?based volumetric iodine?uptake (VIU) in the evaluation of chemotherapy efficacy in advanced gastric cancer. Methods Inclusion criteria of subjects: (1) without previous systematic therapy; (2) with complete clinical information before and after chemotherapy; (3) without contraindications of chemotherapy. Exclusion criteria of subjects: (1) unfinished duration and times of chemotherapy; (2) unmeasurable primary lesions; (3) poor imaging quality or poor gastric filling. Clinical and image data of 52 patients with advanced gastric cancer who were diagnosed by pathology from gastroscopic biopsy, and needed chemotherapy evaluated by imaging and clinical information in the First Affiliated Hospital of Wenzhou Medical University from February 2017 to February 2018 were collected and analyzed. Of 52 patients, 38 were male and 14 were female with the median age of 65 (31?88) years old. All the patients underwent a dual?energy, dual phase?enhanced CT scanning before chemotherapy and after the third chemotherapy session. The parameters of the lesions measured before and after chemotherapy in portal vein phase were as follows: the maximum diameter (the largest diameter among those measured in the cross?sectional, coronal, and sagittal planes), average CT value (the regions of interest were manually pinpointed under cross?sectional planes with largest diameter of the tumor, which did not include regions less than 2 mm to the edge of the tumor) and VIU (lesion volume × iodine concentration). The change rates of maximum lesion diameter, average CT value and VIU before and after chemotherapy were calculated [(post?chemotherapy parameters-pre?chemotherapy parameters) / pre?chemotherapy parameters]. The efficacy of chemotherapy was evaluated by RECIST 1.1 (the change of maximum tumor diameter after chemotherapy), Choi (the change of average CT value after chemotherapy) and VIU (the change of VIU after chemotherapy), respectively, which was categorized by complete response (CR), partial response (PR), stable disease (SD) and progressive disease (PD). Patients with CR, PR, and SD were assigned to the effective group, while those with PD were classified as the ineffective group. Paired t?test or Wilcoxon signed ranks test was used to compare the changes of parameters before and after chemotherapy, whereas Spearman correlation analysis and Kappa test were used for the correlation analysis and the consistency test between the three evaluation criteria ( Kappa≥0.75 indicated good consistency). Results After chemotherapy, the average CT value [(74.01±16.75) HU vs. (81.06±15.87) HU, t=2.202, P=0.030] and median VIU (668.53×102 μg vs. 272.52×102 μg, Z=4.761, P<0.001) decreased significantly, while the difference of the maximum diameter was not statistically significant [(66.71±34.49) mm vs. (78.45±35.62) mm, t=1.708, P=0.091]. The median change rate of VIU (–53.33%) was greater than that of CT values (–5.75%) with significant difference (Z=-5.408, P<0.001). According to the RECIST 1.1 criteria, 47 patients (90.4%, including 19 with PR and 28 with SD) were effective and 5 patients (9.6%) were ineffective. According to the Choi criteria, 45 patients (86.5%, including 37 with PR and 8 with SD) were effective and 7 patients (13.5%) were ineffective. According to the VIU criteria, 46 patients (88.5%, including 41 with PR and 5 with SD) were effective and 6 patients (11.5%) were ineffective. Efficacy comparison among these three criteria showed no significant difference (χ2=0.377, P=0.828). As compared to RECIST 1.1 evaluation, the proportion of PR evaluated by Choi and VIU was significantly higher (χ2=16.861, P<0.001), whereas the proportion of SD was significantly lower (χ2=24.089, P<0.001). There was no significant difference in the proportions of PR and SD between VIU and Choi criteria (χ2=0.887, P=0.346). Consistency and correlation analysis showed that the VIU and Choi evaluation criteria presented the highest consistency and correlation ( Kappa=0.912, P<0.001; r=0.916, P<0.001). Conclusion VIU is a feasible parameter for the evaluation of chemotherapy efficacy in advanced gastric cancer, and may be more sensitive than the evaluation criteria based on maximum diameter or change of CT value in the tumor.

Objective To explore the value of dual?energy CT?based volumetric iodine?uptake (VIU) in the evaluation of chemotherapy efficacy in advanced gastric cancer. Methods Inclusion criteria of subjects: (1) without previous systematic therapy; (2) with complete clinical information before and after chemotherapy; (3) without contraindications of chemotherapy. Exclusion criteria of subjects: (1) unfinished duration and times of chemotherapy; (2) unmeasurable primary lesions; (3) poor imaging quality or poor gastric filling. Clinical and image data of 52 patients with advanced gastric cancer who were diagnosed by pathology from gastroscopic biopsy, and needed chemotherapy evaluated by imaging and clinical information in the First Affiliated Hospital of Wenzhou Medical University from February 2017 to February 2018 were collected and analyzed. Of 52 patients, 38 were male and 14 were female with the median age of 65 (31?88) years old. All the patients underwent a dual?energy, dual phase?enhanced CT scanning before chemotherapy and after the third chemotherapy session. The parameters of the lesions measured before and after chemotherapy in portal vein phase were as follows: the maximum diameter (the largest diameter among those measured in the cross?sectional, coronal, and sagittal planes), average CT value (the regions of interest were manually pinpointed under cross?sectional planes with largest diameter of the tumor, which did not include regions less than 2 mm to the edge of the tumor) and VIU (lesion volume × iodine concentration). The change rates of maximum lesion diameter, average CT value and VIU before and after chemotherapy were calculated [(post?chemotherapy parameters-pre?chemotherapy parameters) / pre?chemotherapy parameters]. The efficacy of chemotherapy was evaluated by RECIST 1.1 (the change of maximum tumor diameter after chemotherapy), Choi (the change of average CT value after chemotherapy) and VIU (the change of VIU after chemotherapy), respectively, which was categorized by complete response (CR), partial response (PR), stable disease (SD) and progressive disease (PD). Patients with CR, PR, and SD were assigned to the effective group, while those with PD were classified as the ineffective group. Paired t?test or Wilcoxon signed ranks test was used to compare the changes of parameters before and after chemotherapy, whereas Spearman correlation analysis and Kappa test were used for the correlation analysis and the consistency test between the three evaluation criteria ( Kappa≥0.75 indicated good consistency). Results After chemotherapy, the average CT value [(74.01±16.75) HU vs. (81.06±15.87) HU, t=2.202, P=0.030] and median VIU (668.53×102 μg vs. 272.52×102 μg, Z=4.761, P<0.001) decreased significantly, while the difference of the maximum diameter was not statistically significant [(66.71±34.49) mm vs. (78.45±35.62) mm, t=1.708, P=0.091]. The median change rate of VIU (–53.33%) was greater than that of CT values (–5.75%) with significant difference (Z=-5.408, P<0.001). According to the RECIST 1.1 criteria, 47 patients (90.4%, including 19 with PR and 28 with SD) were effective and 5 patients (9.6%) were ineffective. According to the Choi criteria, 45 patients (86.5%, including 37 with PR and 8 with SD) were effective and 7 patients (13.5%) were ineffective. According to the VIU criteria, 46 patients (88.5%, including 41 with PR and 5 with SD) were effective and 6 patients (11.5%) were ineffective. Efficacy comparison among these three criteria showed no significant difference (χ2=0.377, P=0.828). As compared to RECIST 1.1 evaluation, the proportion of PR evaluated by Choi and VIU was significantly higher (χ2=16.861, P<0.001), whereas the proportion of SD was significantly lower (χ2=24.089, P<0.001). There was no significant difference in the proportions of PR and SD between VIU and Choi criteria (χ2=0.887, P=0.346). Consistency and correlation analysis showed that the VIU and Choi evaluation criteria presented the highest consistency and correlation ( Kappa=0.912, P<0.001; r=0.916, P<0.001). Conclusion VIU is a feasible parameter for the evaluation of chemotherapy efficacy in advanced gastric cancer, and may be more sensitive than the evaluation criteria based on maximum diameter or change of CT value in the tumor.

Objective To observe the immunoglobulin A secreting cells (IgASCs) and secretory IgA (sIgA) level in jejunum of mice infected with plerocercoids,and to understand the roles of resistance to invasion processes of the plerocercoids.Methods A total of 100 Kunming mice (half males and half females) were chosen,the weight was 20-25 g,they were randomly divided into control and experiment groups according to their body weight via the random number table method,50 per group.Mice of experiment group were fed each with 5 plerocercoids in snakes,and mice of control group were not infected,testing time and methods were the same in the two groups.Ten mice were randomly sacrificed from one group on days 1,7,14,28 and 56 after infection,to collect empty intestinal juice and jejunal segment.The immunohistochemical method was used to examine the quantity of IgASCs in jejunal mucosa,while enzyme-linked immunosorbent assay (ELISA) was applied to test the level of slgA of jejunal fluid.Results The IgASCs were distributed in lamina propria of the jejunal mucosa,and the percentage of positive IgASCs reached the peak value [(64.24 ± 0.60)％] at d 1 after infection in experiment group,then decreased,and it was lower than control group at d 14 [(41.98 ± 0.42)％ vs (43.52 ± 0.94)％,t =-4.727,P ＜ 0.01].The sIgA level reached the peak value [(22.05 ± 1.43) mg/L] at d 7 after infection in experiment group,then decreased,and there was no statistical significant difference between control and experiment groups at d 56 [(20.00 ± 0.42) mg/L vs (21.26 ± 2.59) mg/L,t =1.516,P ＞ 0.05].There was a positive correlation between the percentage of positive IgASCs in the jejunal mucosa and sIgA level in the jejunal fluid at d 7 after infection (r =0.663,P ＜ 0.01),and there was a negative correlation between them at d 14 after infection (r =-0.542,P ＜ 0.05).Conclusion The plerocercoids infection might induce high level expressions of IgASCs and sIgA,they show positive correlation at d 7 after infection.

OBJECTIVETo observe the change of postoperative fatigue in rats after the effect of branched chain amino acid(BCAA) and associated antagonists on central neurotransmitter 5-HT metabolic pathway, and to investigate the role of 5-HT in the development of postoperative fatigue syndrome(POFS).

METHODSFifty SD rats were randomly divided into sham operation group(C group, n=10), model group(M group, n=10), L-type amino acid transporter inhibitor group(L group, n=10), 5-HT uptake inhibitor group(F group, n=10) and branched chain amino acids(B group, n=10). The rats in the C group and the M group were injected with normal saline, while other three groups were respectively injected with BCH, fluoxetine, BCAA(val:leucine:isoleucine=5:3:2), on preoperative 1 h, postoperative day 1, 2, 3, 4. The rats, except for those in the C group, underwent resection of 70% of the middle small intestine with end-to-end anastomosis. General status of the rats was observed before and after surgery. Morris water maze test, including the hidden platform test and search space test (detecting the learning ability of rats) and tail suspension test (detecting physical endurance of rats) were used to evaluate the degree of POFS from postoperative day 1 to day 7. Concentration of tryptophan(TRP), 5-HT, 5-hydroxyindoleacetic acid (5-HIAA) in different position of brain(hippocampus, striatum, hypothalamus) of rats were measured by high performance liquid chromatography(HPLC) at postoperative day 8.

RESULTSAs compared to the M group, other four groups showed better general condition and less fatigue. In the hidden platform test, M group showed the least time of crossing platform as compared to other four groups(all P<0.05). Meanwhile, M group and B group performed the longer incubation period than C group and L group(all P<0.05). In search space test, M group and B group showed less time of crossing platform, but there were no significant differences among the groups(all P>0.05). In tail suspension test, M group and F group showed lower score of physical strength than L group and B group(all P<0.05). Levels of TRP in the L, F, B groups were lower compared to the M group(all P<0.01) in brain tissue. The least concentration of striatum 5-HT was found in the C group but there were no significant differences among the M, L, F and B groups. Level of 5-HIAA in the M group, only in hypothalamus, was higher than that in the F group(P<0.05), but no significant differences between the M group and the L and B groups were found.

CONCLUSIONBCAA and associated antagonists (BCH, fluoxetine) can improve POFS by reducing the absorption of TRP that results in decreased synthesis of central 5-HT.

Amino Acids, Branched-Chain ; pharmacology ; Animals ; Fatigue ; drug therapy ; Intestine, Small ; surgery ; Postoperative Period ; Rats ; Serotonin ; metabolism ; Serotonin Antagonists ; pharmacology ; Tryptophan

Objective To observe the change of postoperative fatigue in rats after the effect of branched chain amino acid (BCAA) and associated antagonists on central neurotransmitter 5-HT metabolic pathway, and to investigate the role of 5-HT in the development of postoperative fatigue syndrome (POFS). Methods Fifty SD rats were randomly divided into sham operation group (C group, n=10), model group (M group, n=10), L-type amino acid transporter inhibitor group (L group, n=10), 5-HT uptake inhibitor group (F group, n=10) and branched chain amino acids (B group, n=10). The rats in the C group and the M group were injected with normal saline, while other three groups were respectively injected with BCH, fluoxetine, BCAA(val∶leucine∶isoleucine=5∶3∶2), on preoperative 1 h, postoperative day 1, 2, 3, 4. The rats, except for those in the C group, underwent resection of 70% of the middle small intestine with end-to-end anastomosis. General status of the rats was observed before and after surgery. Morris water maze test, including the hidden platform test and search space test (detecting the learning ability of rats) and tail suspension test (detecting physical endurance of rats) were used to evaluate the degree of POFS from postoperative day 1 to day 7. Concentration of tryptophan (TRP), 5-HT, 5-hydroxyindoleacetic acid (5-HIAA) in different position of brain (hippocampus, striatum, hypothalamus) of rats were measured by high performance liquid chromatography(HPLC) at postoperative day 8. Results As compared to the M group, other four groups showed better general condition and less fatigue. In the hidden platform test, M group showed the least time of crossing platform as compared to other four groups (all P<0.05). Meanwhile, M group and B group performed the longer incubation period than C group and L group (all P<0.05). In search space test, M group and B group showed less time of crossing platform, but there were no significant differences among the groups (all P>0.05). In tail suspension test, M group and F group showed lower score of physical strength than L group and B group(all P<0.05). Levels of TRP in the L, F, B groups were lower compared to the M group (all P<0.01) in brain tissue. The least concentration of striatum 5-HT was found in the C group but there were no significant differences among the M, L, F and B groups. Level of 5-HIAA in the M group, only in hypothalamus, was higher than that in the F group (P<0.05), but no significant differences between the M group and the L and B groups were found. Conclusion BCAA and associated antagonists (BCH, fluoxetine) can improve POFS by reducing the absorption of TRP that results in decreased synthesis of central 5-HT.

Objective To observe the change of postoperative fatigue in rats after the effect of branched chain amino acid (BCAA) and associated antagonists on central neurotransmitter 5-HT metabolic pathway, and to investigate the role of 5-HT in the development of postoperative fatigue syndrome (POFS). Methods Fifty SD rats were randomly divided into sham operation group (C group, n=10), model group (M group, n=10), L-type amino acid transporter inhibitor group (L group, n=10), 5-HT uptake inhibitor group (F group, n=10) and branched chain amino acids (B group, n=10). The rats in the C group and the M group were injected with normal saline, while other three groups were respectively injected with BCH, fluoxetine, BCAA(val∶leucine∶isoleucine=5∶3∶2), on preoperative 1 h, postoperative day 1, 2, 3, 4. The rats, except for those in the C group, underwent resection of 70% of the middle small intestine with end-to-end anastomosis. General status of the rats was observed before and after surgery. Morris water maze test, including the hidden platform test and search space test (detecting the learning ability of rats) and tail suspension test (detecting physical endurance of rats) were used to evaluate the degree of POFS from postoperative day 1 to day 7. Concentration of tryptophan (TRP), 5-HT, 5-hydroxyindoleacetic acid (5-HIAA) in different position of brain (hippocampus, striatum, hypothalamus) of rats were measured by high performance liquid chromatography(HPLC) at postoperative day 8. Results As compared to the M group, other four groups showed better general condition and less fatigue. In the hidden platform test, M group showed the least time of crossing platform as compared to other four groups (all P<0.05). Meanwhile, M group and B group performed the longer incubation period than C group and L group (all P<0.05). In search space test, M group and B group showed less time of crossing platform, but there were no significant differences among the groups (all P>0.05). In tail suspension test, M group and F group showed lower score of physical strength than L group and B group(all P<0.05). Levels of TRP in the L, F, B groups were lower compared to the M group (all P<0.01) in brain tissue. The least concentration of striatum 5-HT was found in the C group but there were no significant differences among the M, L, F and B groups. Level of 5-HIAA in the M group, only in hypothalamus, was higher than that in the F group (P<0.05), but no significant differences between the M group and the L and B groups were found. Conclusion BCAA and associated antagonists (BCH, fluoxetine) can improve POFS by reducing the absorption of TRP that results in decreased synthesis of central 5-HT.